Nympheum

A nymphaeum or nymphaion (Ancient Greek: νυμφαῖον), in ancient Greece and Rome, was a monument consecrated to the nymphs, especially those of springs.

These monuments were originally natural grottoes, which tradition assigned as habitations to the local nymphs. They were sometimes so arranged as to furnish a supply of water, as at Pamphylian Side. A nymphaeum dedicated to a local water nymph, Coventina, was built along Hadrian's Wall, in the northernmost reach of the Roman Empire. Subsequently, artificial grottoes took the place of natural ones.

The nymphaeum in Jerash, Jordan (illustration, right), was constructed in 191 AD. The fountain was originally embellished with marble facing on the lower level, painted plaster on the upper level, and topped with a half-dome roof, forming a giant niche. Water cascaded through seven carved lion's heads into small basins on the sidewalk.

The nymphaea of the Roman period, which extended the sacral use to purely recreational ones, were borrowed from the constructions of the Hellenistic east. The majority of them were rotundas, and were adorned with statues and paintings. They served the threefold purpose of sanctuaries, reservoirs and assembly-rooms. A special feature was their use for the celebration of marriages. Such nymphaea existed in Corinth, Antioch and Constantinople; the remains of some twenty have been found in Rome and many in Africa. The so-called exedra of Herodes Atticus (which corresponds in all respects to a nymphaeum in the Roman style), the nymphaeum in the palace of Domitian and those in Hadrian's Villa in Tivoli (Tibur) — five in number — may be specially mentioned.

...
Wikipedia