Fort, Fortress, Foxhole, Gallery, Garrison, Grotto, Hold, Hole, Hutch, Keep, Lair, Library, Locker, Magazine, Mine, Moat, Parallel, Peel, Pillbox, Post, Rack, Repertory, Repository, Reservoir, Rick, Sap, Sewer, Shelf, Shelter, Stack, Storage, Store, Storehouse, Storeroom, Stronghold, Subway, Tank, Tower, Treasury, Trench, Tunnel, Vat, Vault, Ward, Warehouse, Warren, Archives, Arsenal, Attic, Bank, Basement, Bastion, Bay, Beachhead, Bin, Bookcase, Box, Bridgehead, Burrow, Buttery, Castle, Cave, Cavern, Cellar, Chest, Citadel, Closet, Concealment, Conservatory, Cove, Cover, Covert, Crate, Crib, Cupboard, Depository, Depot, Ditch, Dock, Drawer, Dugout, Dump, Earth, Entrenchment, Exchequer, Fastness