HEMICYCLE (Gr. iw*i-, half, and KuxXos, circle), a semicircular recess of considerable size which formed one of the most conspicuous features in the Roman Thermae, where it was always covered with a hemispherical vault. A small example exists in Pompeii, in the street of tombs, with a seat round inside, where those who came to pay their respects to the departed could rest. An immense hemicycle was designed by Bramante for the Vatican, where it constitutes a fine architectural effect at the end of the great court.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)