This system became the underground passages of the 13th century and were only turned off in 1902.

People could live in the underground passages and room for several days without the need of going outside.

Under the red one is the entrance to an underground passage.

Going down this way could only lead to some underground passage or to the water.

The underground passage is currently the only one in the city.

I've gone crawling around in some underground passages now and then.

Beyond was the heavy door that covered the underground passage.

It was possible to access the building through an underground passage.

There was also an underground passage that led to the river from the town.

The old and new buildings will be joined by an underground passage.