Root observes that the U-boat is like a tunnel bored out of the sea and lined with hardware.

Descending the staircase, a commuter sees a cavernous tunnel lined with white tile.

The tunnel expanded, becoming a series of galleries, each lined with the rainbow fungi.

As far as they could see ran a tunnel lined with seamless metal.

This tunnel was small but lined with concrete and well lighted.

They led into a long, high tunnel lined with archways and, currently, full of steam.

It was not, as she might have expected, a cave of earth, but rather a wide, open-ended tunnel lined with cut and dressed stone.

The tunnel is 13.1 miles (21.1 km) long and has a concrete lined diameter of 9.75 feet (2.97 m).

A tunnel now led to the tomb which was itself a large underground dome, supported by stonework but lined with bronze.

The hallway behind the offices was cool and dank, a tunnel lined with gray rock foam.