Sanctuary of Heracles was a large paved court surrounded by buildings on three sides and with the principal altar in the centre. It wouldn’t have been as separate from the rest of the town as many sanctuaries, and would have been part of the town’s landscape, immediately apparent to the citizens. The 5th century re-buildings were on a much larger scale than the original 6th century rooms.
As you stand at the gate of Silenus, at the entrance to the sanctuary, the temple of Heracles is at the opposite end, at the very North -it would have been on a raised platform. Originally, it was just a single chambered naos, but was later embellished with a wide colonnade on all sides, giving it a square form, slightly different from the traditional rectangular temples, but the colonnade on all sides is very traditionally Greek.
To the west and at the front of this temple was the stepped and porched entrance to the temenos – this was the last addition to the sanctuary, in the 2nd century BC. It opened onto a paved court with the stepped altar in its centre, and a long gallery hall forming the opposite border (along to the right from the entrance at the gate of Silenus).
The South side was occupied by a porticoed building containing official administrative offices for the sanctuary and the banqueting rooms – where the important early summer feast the Heracleia was celebrated.
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.