What is the semi-circular or rectangular recess often set into a building's facade or at the rear of a peristyle garden called?

The term that describes a semi-circular or rectangular recess often found in a building's facade or at the rear of a peristyle garden is known as an exedra. This architectural feature is typically used for relaxation or social gatherings, providing an area for seating and often enhancing the aesthetic appeal of the space with a distinctly curved or angular form.

In classical architecture, an exedra was commonly incorporated into public spaces like forums and was designed to offer a vantage point—both visually and socially—for those who would gather there. Its function connects deeply with the ideas of Greek and Roman public and private life, as it provided an ideal setting for conversation and contemplation.

Herms are typically markers or boundary stones with a bust and are not related to recesses in walls. Oecus refers more to a reception room or a large hall rather than an architectural recess. An Andron is a passageway or corridor, particularly in a Greek house, which also does not align with the definition of an exedra. Thus, the identification of the term exedra captures the essence of the architectural feature in question accurately.