hello and welcome to switzerland. i m in the town of chateau d oex. it is known for its gruyere cheese, which is delicious, and the international balloon festival, held in the valley behind me every winter. but let s start somewhere a little warmer. mexico city s ancient canal network was first built by the aztecs. it stretches 180 kilometres and these days the whole district of xochimilco is a unesco world heritage site but one that could do with a bit of a clean up. we sent eva zu beck there to find out why. check out all these amazing boats, they re so colourful. these are called trajineras.
international balloon festival held in the valley behind me every winter. let s start somewhere a little warmer. mexico city s ancient canal network was built by that aztecs. now it is a unesco heritage site, but one thing to do with a bit of a clean up. we went there to find out why. out here in the more remote areas of the wetlands, pollution is danger in one of mexico s most beloved animals. the strange looking axolotl. what is so special about these creatures?