These arcade dens were called "fornices," from which comes our generic fornication.
Allusion has already been made to the fornices under the circus.
Their name, fornices, at last became synonymous with lupanar, and we have borrowed from it our generic word fornication.
fornix for·nix (fôr'nĭks)
n. pl. for·ni·ces (-nĭ-sēz')
An arch-shaped structure, especially the arch-shaped roof of an anatomical space.
The compact bundle of white fiber by which the hippocampus of each cerebral hemisphere projects to the opposite hippocampus and to the septum, the anterior nucleus of the thalamus, and the mamillary body.