It's a big rock with great tunnels connecting the buildings.

After some time they came to a large cavern with several tunnels leading out.

To the east of the village there is a hill riddled with tunnels.

The south and west walls were very thick, with embedded tunnels.

One of them is about 26 feet high, with huge subterranean tunnels beneath it.

The food court connects to other nearby structures with tunnels.

This entire area could be riddled with tunnels and we'd never know it.

However mining continued with tunnels extending out under the sea.

Then the tunnel opened out, and we were in a sort of round chain her with other tunnels opening off it.

The section gets a new 72.1 km long alignment with several tunnels.