The Benedictine Basilica of Sant’Angelo in Formis stands at the foot of Mount Tifata, on the remains of a temple dedicated to Diana Tifatina. The pagan temple’s ruins, found in 1877, show that the plan of the basilica traces its perimeter. The construction date of the primitive church of Sant’Angelo in Formis is unknown, but it is placed at the end of the sixth century AD. and it’s attributed to the Lombard princes.
We do know that a church certainly existed in the 10th century, when the Cassinese monks were granted a permission to build a monastery there. In 1072 the ownership of the building passed from Richard I, Prince of Capua and Count of Aversa, to the Abbey of Montecassino, ruled in those years by Abbot Desiderio (1027-1087). Under his rectorate, the Basilica of Sant’Angelo in Formis was rebuilt and equipped with a wall decoration whose remains today represent one of the most important monuments of the Middle Ages.
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.