The Castello Svevo di Catania is a large building complex with short wings. Each side measures about 50 metres, and at the four corners there are round towers just over 10 metres. With high-pitched semi-cylindrical towers just two medians have been preserved, but is certain even the existence of the other two missing. The walls, made of lava rock, have a thickness of 2.50 metres.
The exterior of the castle is marked by numerous openings in large part after the original project. Inside, the building originally svevo had four ground-floor building with wings rectangular covered environments each by three cross-vaults; four square rooms, which are also covered by cruises, connected between them. Its original appearance kept in the North wing that preserves intact the triumph of five cruises. According to a recent contribution the original plan foresaw an upper floor only on Northern air, unlike the one that claimed Joseph lamb, according to which the upper floor had been expected in the drawing of Federico II, created and then transformed between the 15th and 16th centuries.
The castle is the seat of the Civic Museum from October 20, 1934. It houses the civic collections where there are archaeological sections medieval, Renaissance and modern. There are conserved 8043 pieces between archeological finds, inscriptions, coins, sculptures, paintings, clay sarcophagi Greeks, Romans, mosaics. There are in fact various archaeological finds from the city and from the territories of Catania, Paternò, Santa Clara, Lentini, Rome, Trapani, Caltagirone (ceramics), Ercolano, Camarina. Also it keeps the clay statue of a Kore found to Inessa-Civita in territory of Paternò. The Museum contains the Latin inscription found in the source of the ancient Greek-Roman aqueduct at the Benedictine monastery of Santa Maria di Licodia in territory of Paternò.
The Castle also houses, in the splendid rooms located on the ground floor, a legacy of illustrious donations Catania, works from churches and convents abolished, by the Benedictines and Museum from the collection of the Prince of Biscari. The core of this illustrious Carter collection consists of archaeological material from excavations in Catania and from purchases made in Naples, Rome, Florence. Among the most valuable pieces in the collection some gorgeous vases, terracotta archaic penthouses and a large group of bronzes.
The Castle also often hosts exhibitions of national and international significance.