Town officials said they never knew the underground structures existed.

The underground structure was damaged by fire in the early 1990s.

They're coming from an underground structure beneath one of the larger population centers.

City officials say it was the company's responsibility to check for underground structures.

Unfortunately the purpose of these small underground structures is also obscure.

The station is an underground structure with one island platform and two exits.

I was now close to the great underground archival structure which seemed to form my goal.

She pulled him to a darker area of the underground structure.

The diagram below shows the relationship between these underground structures in a typical mountain tunnel.

It is planned as an underground three-story structure to include offices.