Trim Castle, the largest Anglo-Norman castle in Ireland, was constructed over a thirty-year period by Hugh de Lacy and his son Walter. Hugh de Lacy was granted the Liberty of Meath by King Henry II in 1172 in an attempt to curb the expansionist policies of Richard de Clare, (Strongbow). Construction of the massive three storied Keep, the central stronghold of the castle, was begun c. 1176 on the site of an earlier wooden fortress. This massive twenty-sided tower, which is cruciform in shape, was protected by a ditch, curtain wall and moat.
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.