The building lies on top of a large tunnel network.

The network of tunnels under the prison was opened to the public on 7 June 2005.

Whether this tunnel network was developed during the 1980s is unknown.

There is a bus station, which makes use of a tunnel network.

They passed it and entered a new network of tunnels.

Matthews looked around and saw they were actually in a network of tunnels.

Indeed, in another moment he broke through to the tunnel network of the princess.

This tunnel network has mainly been used for military purposes.

Part of the tunnel network is now open to the public as a tourist attraction.

That was what they called the little entrances to a tunnel network.