amanda ruggeri explores the new technology that is allowing archaeologists to explore the hundreds of mayan structures that are still hidden beneath the amazon. located in biosphere reserve is the largest ra i nforest located in biosphere reserve is the largest rainforest north of yarmouth on and one of the world's most important hotspot for biodiversity. — guatemela. it is also once the heart of the maya civilisation. today, thousands of houses, fortifications and temples and other structures lie hidden underneath the jungle. some archaeologists are determined to change that. they have devoted their careers to getting the jungle to give up its secrets. and new technology has revealed that despite decades of work, they have only begun to scratch the surface. there's a deep hole, and that's where they're digging right now. car starting. don't let me down. the maya city of holmul has been an obsession of archaeologist francisco estrada belli's for the last 20 years. he calls it the gift that keeps on giving. let's try not to get stuck. yeah. in recent years, his work has been aided by the use of lidar, a technology currently transforming archaeology. i've come to holmul, on the border with belize, to learn more about what estrada belli has discovered. this was one of the most populous places on earth a thousand years ago, if you think about it. we're already estimating eight to 11 million people in an area of 9,000 km2. and yet they were using very sustainable practices so that they could do this for 2,000 years. and so, you started excavating... ..in holmul in 2000. that was our first season, yeah. it was very adventurous. we worked for two weeks, and then it started raining. we didn't have any cars and the roads were all flooded, so we got on out on horses. the city of holmul dates back to 800 bc. it was abandoned 1,700 years later. one of its mysteries that estrada belli has been trying to solve — its empty tomb. i think i know why they abandoned it, because the date of the building matches with a guy who's supposed to be from here, being sacrificed at tikal, in the year 748. 0k... and after that, pretty much all monumental construction stopped here. so, tell me what that would have meant. so, tikal was defeating its archenemy, the snake kingdom, and they already defeated the actual snake kings and now they were going after its former allies. this is historical archaeology. we don'tjust talk about processes any more and theories, now we talk about specific events, specific people. because we can read the inscription. and yet, this tomb was almost destroyed before estrada belli, or any another archaeologist, were able to discover it. and here is the tomb chamber. wow. looters came and dug a hole right behind this doorway. and they missed by the structure with the freeze by 27 metres, i'll show you. so that's the freeze right there... whoa! so that's the corner image of one of the dead kings. you can imagine what they would have done. they would have said, oh, my gosh, there's definitely something cool behind this and they would just blast through it. it's all there and it goes for eight metres that way and another five this way, has been damaged on purpose by the ancient maya. nothing else, really, is damaged in the whole carving. just his face, his necklace, a little ceremonial head. the maya believed everyone had a soul, including images of people and things. and so when they were burying something, they would let the soul out by killing the image. that's the god of the underworld. and he's holding something. he's holding a hieroglyph. it's two syllables. two words, really. 0ne means the first, and one means the food. so he's holding the first of it and he's offering it to him. i love the faces on this. so that's the eye? that's the spiral eye. he's got blue under the eyes. he's tired. laughter. he's been up all night because he's the god of the night sky. and this here is the glyph that says... he's the vessel of the snake kings. what did you feel in that moment when you realised that? when i saw the glyph, i thought, well, my careerjust made a big turn. exactly! it's like, jackpot! estrada belli was lucky to find this freeze. the jungle doesn't make for especially easy archaeology. 100 years ago, an archaeologist from harvard first came to holmul and discovered these temples, but he missed the oldest carving which dates all the way back to 350 bc. the notes were rather incomplete because the archaeologist died shortly after working here, by a mysterious disease that he contracted here. he returned from here with a massive sore on his nose which never healed. that's what happens with this bug. eventually he died, he never finished his reports. it was actually published by one of his friends at harvard, posthumously. they forgot to mention this tunnel, and he had found the window of an earlier pyramid and stopped. so, we kept digging and there's this massive carving that explained what the temple is all about. so are these beetles still around? yes. 0h, great! it's called the assassin bug. good, i'm glad we're going in now. welcome to the underworld. it even made a sound. turn the light on. watch your step. we're going to walk around the exterior and go to the front. and this is the front of the building. whoa! god, it's a lot bigger than i was expecting. yeah, it's all perfectly preserved. wow. ..for 2,400 years. and what you have is a massive head of an earth monster with the mouth open, these are the teeth. and here inside the mouth of this monster is the face of an old man. and even today the maya in guatemala that worship an old man, it has the same wrinkles, the teeth like that. it's the image of the god of the underworld. it's not going to change. jungle creatures and diseases are just two of the problems that archaeologists have had to face. but historically, the bigger threats to the rain forest and its archaeology have been logging and looting. this is el diablo. the devil. the devil, yeah. laughs. we don't know why they choose that name. it's an early classic building, we call it between 300 ad to 600 ad. wow. now we're going to go and try to see some of the earliest version of this building. and what was it used for? this was the funerary temple. here's where the remains of the fierce king of el zotz rests. this devil temple was allegedly named because the sides are dangerously steep. but maybe more fitting is that its king who ruled in the fourth century ad was buried with the remains of six sacrificed children. two metres below here, that's where we found the tomb. yeah, that's where we found the tomb, two metres away. so i'm standing on top of a king's tomb? yes, from 370.380 ad. but nothing's in there any more? no, we removed, we excavated, and everything now is in a national museum. the looters hadn't gotten to it, so everything was still there? everything still there, we found it, we found it, the chamber was completely sealed. when we open, we still feel that cold breeze and like a smell, like something was in the putrefaction process, when we open it. in 2010, when we found the tomb of the fierce king of el zotz, we were working on it. unfortunately, looters can come and they are really well organised and can take everything from you. one day we hired a group of guards to protect it, but it didn't work because some of them tried to too. i confronted them, one of them put his gun shot. at the time, i think i was a good liar. itold him, you know, this is a computer. we have internet, which we don't have, and we are filming everything. and that's when it stopped. another major challenge for the maya biosphere reserve is illegal logging, often tied to drug trafficking. and when the jungle is cleared, it doesn't just affect the animals in the rainforest, but the maya sites, which are often irretrievably damaged. they will clear the forest around archaeological sites, plant the marijuana, loot the sites while the marijuana was growing and then collect to harvest. and put all they got on small planes to go to the us. several illegal activities are still going on in guatemala. illegal logging, which is not a problem here specifically, but in other parts of this region, it's a big problem. drug trafficking. we're fortunate here at holmul, but out at western guatamala, they cut the forest to build airstrips, airplanes from columbia, land there, and it's a trans shipment place to go across to mexico and from there to the us, and they burnt all the forest in the process. whereas this area has done much better because it was given in concession to local communities for sustainable logging. so in the last 20 years, the local communities have stopped the drug trafficking, the land invasions, the deforestation, and that's why sites like this are still covered by forest. we think what we have in place here works much better because the local communities are empowered and have an incentive to protect the forest. which is the sustainable logging. for as long as they can continue, they will protect the forest. this man is vice president of the arbol verde concession which has been given to local residents for sustainable logging. while logging might seem an anathema to the forest, it turns out that concessions like these can have quite the opposite effect. by being run with strict adherence to sustainable management principles, community concessions like this one have actually protected the reserve. one of the biggest challenges to archaeologists in the maya biosphere reserve isn't logging or even looting. it's a fact that it's extremely difficult to find or identify structures in a jungle as thick and wild as this one. and that's where a technology that's relatively new to archaeology, lidar, has been transformative. so, this hill is supposedly a pyramid. they think it might be may be as big as the great pyramid, the mundo perdido, it's definitely steep. it looks like a hill. so, it's pretty amazing that they're able to find that out through lidar. we're right here. 0nly10% of tikal has actually been excavated and discovered? this feels very indiana jones. lidar is a type of remote sensing technology that's used to create extraordinarily detailed 3d maps and representations. in the reserve, lidar is being employed in two ways, from aircraft to create topological maps, and from hand—held scanners to build better 3d models of a particular site or structure. the process of beaming lasers from aircraft, the largest survey, is the initiative of the foundation for mayan cultural and natural heritage. it's amazing. probably a pre—classic structure. it's massive. this is one of the bigger temples of tikal. what is lidar, exactly? what makes it such a great tool? it really strips off the forest canopy with billions of laser beams that map individually, each return, every time they hit something on the surface. that will give tremendous use for the forests and the biomass. and you said billions of laser beams. how many billions of laser beams? i think our first data said 60 billion returns. so, that's an incredible amount of data. and how long did it take to collect that? really, only a couple of weeks. it was something like eight flights. 2,100ka of area is covered in that amount of time. you obviously have a great appreciation for an understanding of how sophisticated the mayans were. yes. but did the lidar increase that understanding even more? yes, the lidar showed without any doubt that we totally underestimated their engineering capabilities in terms of landscape modifications to make the land for sustainable, to irrigate, bringing water to places to cultivate, to stop erosion. it's pretty mind—blowing. that's how i felt. and i thought the mayans were sophisticated already, but not at this scale. one of the sites where lidar has been especially helpful is here, el zotz. lidar is the first step. it shows us everything. it gives us the footprint, but then archaeologists still have to go out, and get there and check it. they have to get there. lidar makes it so that as archaeologists, we don't have to spend all her time figuring out what's there and instead, we can focus in and excavate and addressing questions we want to. so much of our time is spent mapping and just trying to find places, and what lidar‘s shown us is that we weren't very good at it. a lot of sites around here were abandoned at the end of what we call the classic period. around 900, something like that. el zotz had people living here up till the 1300s. we're probably somewhere near the old communal royal, the new spanish road that passed down through central america and supposedly was built on top of a major pre—columbian three way. but no—one has actually pinpointed where that ran through. we wonder will lidar eventually reveal that for us. that will be amazing. the first king of el zotz was such an important character that a temple was created for him so he would never be forgotten. 0nly be careful with these things, they are supporting the roof. when you are here, be careful. if you fall, fall this way. so, don't fall on the sculpture. so this was all from one king? yes. for the first king. this king not only was powerful — we know the extension of his power. lidar is helping us recognise everything this king did to preserve him, his family and his legacy. the creation of a dynasty. so a find like this tells you there is a king, then the lidar helps you realise what the whole context is. yes! and how much even more there is, and how powerful he was. everything they built, we can make more sense of it. and so you have been coming here for 20 years and knew the area very well, but you still hadn't suspected that this was a major wall. i could see it was a while, but i was thinking, what is a while doing here —— wall. when you see it in the context of lidar, it makes more sense. myjob is typically two things. i think it was a 100—metre long wall, i had no idea it continue for seven kilometres! ifa if a causeway, not a wall! —— it is. when you got that lidar data back and started to see all that, what'd you say? i was like oh my god, my god for hours. oh, my god, look at this! oh, my god, look at that! it's very humbling. you think you know what you're doing for all my career. right, yep. and this thing is so much better than what any of us can do. we can do what we do in 20 years in two days. the same work and it's better. the lidar shows how big the rain forest is and how many trees there are with much greater precision. which can be instrumental in conserving the rainforest. hello there. it's going to settle down as we move into the christmas period with high—pressure dominating. we should see quite a bit of sunshine but also some frost. but before we reach that point, we've got quite a bit of rain in the forecast for wednesday, particularly across the southern half of the country, all tied in with this area of low pressure. this is the high pressure that's going to win out for the christmas period, but we have to contend with this first. it's going to bring a lot of cloud across much of england and wales through the day, today. some of it will be heavy in its own, particularly from wales through the midlands across into east anglia, there's a chance of flooding in places as the ground is saturated from all the recent rain here. probably raining everywhere, there will be some drier, brighter spells around, very mild in the south, but it's scotland and northern ireland that will see the best and the brightest, but it will be cold with some wintry showers over the north. now, as that area of low pressure pulls away, we'll start to see, er, northerly gales develop across parts of wales, western england, around the channel for a time, and then we'll see further showers across the northern half of the country. these will be wintry over the high ground. but much colder air starting to sink southwards as we move through wednesday night. you can see a widespread frost across central and northern areas. so, this area of high pressure eventually topples in from the west for christmas eve. quite a few isobars, though, on the chart across the eastern half of the country. so it will be windy here, and that's going to drag in a few showers for christmas eve here. it may leave rain here to lower levels, we could see some wintriness over the higher ground. there'll be one or two dotted around western coasts, but for most it's a cold start but a brighter day — plenty of sunshine across england and wales. a bit of cloud across the far north of scotland. and those temperatures 4—7 degrees, out on the wind across the east it's going to feel pretty raw. and then for christmas day itself, we continue with our area of high pressure. we start to see this weather front, though, arriving later on in the day. but we start christmas morning off on a cold note, under clear skies, we ll see a widespread frost to greet us for christmas morning. and there will be plenty of sparkling sunshine as well, especially for england and wales as we start to see more cloud across the north and west as that weather front i showed you begins to bring some wetter and windier weather, certainly to western scotland. another cold day for christmas day, 4—7 degrees. as we head on into boxing day, it turns much more unsettled, very windy, widespread gales, outbreaks of rain, that also lasting into sunday, with sunshine and showers. welcome to bbc news — i'm mike embley. our top stories: president trump retracts a $900 billion coronavirus relief package agreed to by congress after months of wrangling. the bill they are now planning to send back to my desk is much different than anticipated. it really is a disgrace. france re—opens its border to britain after a two—day closure leaves thousands of lorries stuck in south—east england. and israel heads for its fourth election in two years. parliament failed to meet a deadline to pass a budget. singing and how to sing safely this holiday season, with a little bit of help from scientists.