A circular tunnel with a circular pipe in the middle of it.
The circular tunnel I found at the foot of the stairs has been dug, drilled and plastered with great effort.
The glittering wall stretched for miles, sealing off the circular tunnel completely.
I want the first group to go into the long circular tunnel, back there.
The original, bold plan for Tristan was to include three accelerators in its circular tunnel.
Smaller, circular tunnels branched off like capillaries from an artery.
Its main component is a circular tunnel 54 miles in circumference.
It's a long circular tunnel, a ring around the rock's center of gravity, cored just under the surface.
The men where crouched in a circular tunnel that measured five feet in diameter.
The circular tunnel was about half a mile long with an entrance foyer at each end.
