Each new passageway, even if it is empty or a dead end, leads to a spot where another passageway may start.
Because of concerns that terrorists could adopt the tactic to smuggle radioactive and chemical materials into the United States, a military team checks each underground passageway discovered; no residue from such materials has ever been found.
The floors above the passageway each consisted of a single large room and were connected to the keep, allowing people to move between the two without having to go outside.
Each side of the passageway is lined with thin limestone slabs known as orthostats, placed on end and up to 5 feet high with a coursed dry-stone infill between the slabs.
The Miami tunnel is a "twin-bore" tunnel, with a separate passageway for traffic in each direction.
In each of the rose arches a passageway opens, like the entrance to a garden, to a grave, to the heart of a flower.
M.I.T. seemed to Owen heroic in the grand and mazy scale of its vast central building: a series of buildings interconnected by passageways, each segment known not by a name but by a number.
The layout of ancient Chinese capitals, such as Bianjing, capital of the Northern Song, followed the guidelines in Kao Gong Ji, which specified a square city wall with several gates on each side and passageways for the emperor.
Except for Embankment, which had a sloping passageway down to the platforms, each station was provided with between two and four lifts and an emergency spiral staircase in a separate shaft.
