Architecture

After Frederick returned from the crusade in 1229 a group of important structures were undertaken. In 1239 the emperor charged his 'praepositus aedficiorum', Ricardo da Lentini with completing three buildings which are still standing today. The three structures are alike in the systematic consideration and analysis to the underlying construction ideas as well as the forms of expression. There is to be found a mathematical division of the ground plans of prism-shaped palace into a pattern of 25 squares: 16 in the four-cornered buildings and nine in the courtyard - which may be regarded as a particular characteristic of Hohenstaufen architecture.

The castle measures 50 x 50 meters, with cylindrical corner towers in which are cylindrical spiral staircases. The absence of towers on the side of the building permitted for inclusion of a portal (see below) in the median axis of the front.

Eight inner vaulted squares join the outer squares on each , resulting in 24 squares with pointed arches and rest on 16 columns and 20 pilasters. The 25 square is open and forms the inner courtyard. The supporters for this center square are three bundled half columns. We will encounter more bundled half columns at Castle del Monte. This inner square open courtyard, admits light to the rooms; a technique which will also be repeated in Castle del Monte.

The castle was originally square in shape, each wall being 62 meters long. There were four square towers at each of the corners, two polygonal towers at the centre of the North and South walls and two rectangular ones at the centre of the East and West faces. Of these original eight, only six remain. The walls and towers enclosed a large courtyard, around which were the characteristic low, pointed arches with a false ornamented support. On three sides of the courtyard these arches formed one simple, cross vaulted nave which provided the many entrances to the yard itself. The castle proper could only be entered through the southern end of the courtyard, by way of double nave. In 1590 the isthmus of the peninsula was cut to render the city and the castle more defendable. The island could then be reached by way of three bridges: two of these were draw-bridges going from the island to the mainland. The other was the already existent bridge from the mainland to the island. In 1693, because of an earthquake, an explosion destroyed the castle powder-store and a share of the east side. In the 1893 the castle was converted in a prison and served that purpose until 1978. It is now in restoration.

Where did this square plan originate? The answer can probable be found about 90 mile south of Sicily in north Afirica. Not only did the Normans have contact with north Africa, Roger II controlled the cost from Tripolis to Cap Bon.

Ribat at Susa, Tunisia (below is a good bet).

Ribat was constructed about 796.