The Forum Baths are a ruin of a Roman bath complex in Augusta Treverorum, modern-day Trier. The site was converted in the 4th century CE from some older buildings, dated to around the 2nd century CE. The structure encompassed 8364 m2 The bath house utilized the passive heating of the sun, like many Roman baths, and oriented the caldarium and tepidarium to the south, and the frigidarium to the north.
Along with the other bathhouses, the Forum Baths remained in use through the end of the fourth century. But the complex fell out of use during the early fifth century as Trier was repeatedly sacked during the Migration Period.
In the 13th century, the remains of the bath began being used as a quarry for local buildings. In the 17th and 18th centuries, the Capuchin Order built some of the buildings for their monastery over the eastern part of the bathhouse. In 1802, the monastery was dissolved and nine years later, in 1811, the garden was transformed into a cattle market (German: Viehmarkt), from which the ruins get their name.
References:The Church of St Donatus name refers to Donatus of Zadar, who began construction on this church in the 9th century and ended it on the northeastern part of the Roman forum. It is the largest Pre-Romanesque building in Croatia.
The beginning of the building of the church was placed to the second half of the 8th century, and it is supposed to have been completed in the 9th century. The Zadar bishop and diplomat Donat (8th and 9th centuries) is credited with the building of the church. He led the representations of the Dalmatian cities to Constantinople and Charles the Great, which is why this church bears slight resemblance to Charlemagne's court chapels, especially the one in Aachen, and also to the Basilica of San Vitale in Ravenna. It belongs to the Pre-Romanesque architectural period.
The circular church, formerly domed, is 27 m high and is characterised by simplicity and technical primitivism.