the.com/hidden passage

A door that pretends to be a wall and usually wins.

means A concealed corridor or doorway built into a wall, bookshelf, or other surface, designed to let people or things move unseen between spaces.

from Not a single coined word but a building tradition: 'passage' comes from Old French passage, from passer 'to pass,' rooted in Latin passus, 'step' — the same root giving us 'pace' and 'pass.' 'Hidden' traces to Old English hydan, meaning to conceal, cover, or keep out of sight. The phrase itself owes less to word-history drama and more to architectural history — priest holes in persecuted households, escape routes in castles, smugglers' walls — real spaces built to make a wall lie convincingly.

origin
Castles used them to dodge sieges and spouses
mechanism
Often a bookshelf hinged on a false spine
fiction appeal
Promises the house knows more than you
real estate twist
Now a luxury listing feature, not a secret
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