1m 48s: Lenght

The world's largest underground floodwater diversion facility is an impressive feat of engineering and also an architecturally beautiful space. Through a systems of tunnels flood water from various Tokyo rivers can be channeled through a system of 6.3 kilometres of tunnels. Well worth a visit. More info here: http://www.ktr.mlit.go.jp/edogawa/gaikaku/english/ Recorded in 60fps