Seoul’s secret space: vast mysterious tunnel revealed for the first time

A huge tunnel underneath Seoul, South Korea, which has now become a tourist attraction, with authorities asking for further ideas on how to use it. Photograph: Raphael Rashid/The Guardian

If you look in the right place, beneath the bustling streets in the heart of Seoul, you will come across something unexpected: stalactites.

They hang ominously from the dank ceiling, a witness to the passage of time and decades of neglect.