The Colophon Clinic is an empty clinic that was used by Hangfire as a headquarters in When Did You See Her Last? It is located just outside of the town Stain'd-by-the-Sea.

Years before the series All the Wrong Questions takes place, Colonel Colophon was badly burnt in an explosion. Colophon Clinic was built to treat him and he has lived there ever since. The dark, eerie building has a swimming pool, basement, and a tall turret. Dr. Flammarion worked at the clinic for years.