have we. let me just talk you through some of the mind boggling numbers. right now, i m 60 metres underground, but at its deepest point, this tunnel reaches depths of 65 metres. at its widest point, just up there, it is the width of three london double decker buses, more than seven metres. and it stretches right across london for more than 15 miles from east to west, roughly following the route of the river. so why is it needed? i ve been taking a look, and just a quick warning, some of these pictures may put you off your breakfast. london s sewers are a victorian marble, built over 150 years ago by the engineerjoseph basiljet now it is coping with a larger population,