Bruges is a city with two town squares. The largest one is the Market, the commercial heart of medieval Bruges. The second square is called the 'Burg'. Here was, and still is, the heart of the administrative Bruges.It was here that Count Baldwin I had a fortified castle built to protect the area against the ramping Normans and Vikings. The castle has long since disappeared as well as the main religious building of Bruges, the St. Donatius church, which stood on the opposite site of the town hall. On the site of the church is now a little wall, a partial reconstruction of the choir walls of the church. It was built here after the foundations of St. Donatius had been found back in 1955. The church was erected around the year 900. The central part was octagonal, much like the cathedral of Charlemagne in the German city of Aachen on which it was modeled.