The Tumulus of St. Michel is a megalithic grave mound, located east of Carnac. The 125m long, 60m wide and 10m high mound is the largest grave mound in continental Europe. The age of the monument, and the chronology of the construction of the central burial-chambers and outlying dolmen have been the subject of much speculation. Ancient samples were radiocarbon dated, but the results were too disparate to be significant. Recent excavations point to this large tumulus being constructed in several stages but in a rather short lapse of time, around the middle of the 5th millennium B.C. Today there is a chapel built on top of it.
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.