Exedra

An exedra is a semicircular architectural recess or platform, sometimes crowned by a semi-dome, and either set into a building's façade or free-standing. The original Greek word ἐξέδρα was applied to a room that opened onto a stoa, ringed with curved high-backed stone benches, a suitable place for conversation. An exedra may also be expressed by a curved break in a colonnade, perhaps with a semicircular seat.

The exedra would typically have an apsidal podium that supported the stone bench. The free-standing exedra, often supporting bronze portrait sculpture, is a familiar Hellenistic structure, characteristically sited along sacred ways or in open places in sanctuaries, such as at Delos or Epidaurus. Some Hellenistic exedras were built in relation to a city's agora, as in Priene. Monument architects have also used this free-standing style in modern times.

Source: Wikipedia