passageways, underground, viaducts, caves, sarcophaguses, caverns, crossings, underpass, corn borer moth, bridges, trench, roadbed, shafts, aqueducts, verrazano narrows, caissons, fortifications, alleys, staircases, burrows, bunkers, catacombs, canals, corridors, walkways, overpasses, tramway, sewers, belowground, trestles, ventilation shaft, adits, throughway, reinforced concrete, postholes, overland, pipes, mazes, subway, manhole, guideway, highways, carriages, mineshaft, aboveground, millrace, cellars, alleyways, drawbridges, warren, cloverleafs, channel tunnel, stalactites, excavations, ratlines, elevators, snowshed, aswan dam, wormholes, trains, rockface, jackhammers, archway, bailey bridge, crevices, drainpipes, mines, roads, stairways, entrances, truss bridge, manway, rockwork, aerotrain, potholing, pipelines, skyscrapers, overpass, tombs, cisterns, blowtorches, mousehole, courtyards, sidings, trackway, diggings, dungeons, stalagmites, grottoes, routes, embankments, crevasses, falsework, tram, riverbed, headrace, interchanges, pyramids, doorways, wadis, ducts, quarries, tunnel, galleries, jetties, ditches, conduits, runways, troughs, chutes, drawers, piles, platforms, pockets, reservoirs, stacks, wells

bank martin, bank swallow, bark beetle, carpenter ant, carpenter bee, ephestia, genus ephestia, labyrinth, maze, rabbit warren, riparia riparia, sand martin, warren, web spinner