A limestone cliff appears in front of you with an opening on the lower portion and you proceed through the opening. You are riding a tiny little boat with 10 other people guided by a local boatman, equipped with a handheld light up front. You enter the dark cave with the walls surrounding you, and little by little it opens up into several sections of large chambers with stalactite and stalagmite formations, some of which are utterly enormous. It is surreal to think that you are inside huge cave with a river that is 8.2 km (5.1 mi) long running through it all while being underneath a mountain. Puerto Princesa, Philippines.
In Seoul, the water of The Cheonggye stream became progressively more polluted and in the 1970’s the river bed was turned into a road, then an elevated six-lane motorway was built above it.
In 2005, after 6 years of planning, the road and the stacked expressway was removed. Now a park has replaced the freeway and the water in the river is restored, albeit mainly from groundwater.
Three broken highway abutments have been preserved to memorialize the demolished expressway, “we have to give our education to our descendants not to make the same mistake twice”.
An interesting interview of Kee Yeon Hwang, urban planner and designer, principal author of the masterplan, in the Guardian