The complex consists of Dolmens in Valencia de Alcántara consists of more than 40 dolmens. The most famous of the dolmens is the so-called “El Mellizo” in the little village of Aceña de la Borrega.
This megalithic area is among the largest in Europe. The stone structures are funerary constructions from the Neolithic and Chalcolithic periods, which spanned between the third and fourth millennium BC. At the site, archaeologists have found individual and group burials, as well as funerary goods such as ceramics, ornaments, arrowheads, axes, carvings, and anthropomorphic idols.
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.