The castle was built directly on a rocky bank, in some places cropping out, and is well known for its octagonal shape. Eight octagonal towers are inserted on each of the eight corners. The wall curtains, built in the local calcareous stone, are marked by a string-course moulding. Eight windows with one light open on the lower floor, seven mullioned windows and only one three mullioned window, facing the city of Andria, on the upper one.
The octagonal shaped, courtyard is characterized, as the whole building, by the chromatic contrast between the colours of the utilized materials: coral crushed stone, limestone and marbles. The slab representing a parade of knights and a fragment of an anthropomorphous figure are the only remains of the sculptures once making a fine show there.
On the first floor three French windows open, under which some jutting out elements and some holes utilized, maybe, to hold up a wooden gallery .Very likely it rendered independent the halls, otherwise all communicating in a ring route except the first and the eighth one, separated by a wall in which a small round window was probably used to communicate.
The 16 halls, eight on each floor, have a trapezoidal shape and have been tiled with an ingenious technical solution. The space has been divided into a square central span, covered by a ribbed cross vault held up by semi-columns in coral crushed stone on the ground floor and trilobite marble pillars on the first floor, while the remaining triangularspaces are covered by pointed barrel vaults.
The different keystones of the crosses are decorated by anthopomorphous, zoomorphous and phytomorphous elements.
The two floors are linked up by three winding staircases inserted in as many towers .Some of the towers contain tanks for collecting the rainwater partly conveyed to the large tank sunk in the rock, under the central courtyard.
The toilets are situated in other towers. They are furnished of lavatory and washbasin and placed side by side by little rooms probably used as changing rooms or appointed for housing bathtubs for the ablutions.
Frederick II and his court used to have a great care for their body according to the typical custom of the Arab culture, so beloved by the King.
Although nowadays impoverished, the sculpture set is of very great interest and gives a significant evidence of the former decorative body, once characterized also by a wide chromatic range of the used materials: mosaic tesserae, glazed majolica tiles, glassy paste and wall paintings. At the end of the 1700 and on the first decades of the 1800 some local writers and historiographers could admire and describe the traces of some of them.
Nowadays the two anthropomorphic brackets in the Falconer tower, the Telamones holding up the umbrella-shaped vault in one of the stepped towers, and a fragment of the mosaic floor in the 8 th hall on the ground floor can still be seen there. Two important sculpture fragments are temporarily deposited in the Picture Gallery in Bari. They are a head and an acephalous bust, found during the long lasting restoration work (which didn't give back any traces of the octagonal basin in the middle of the courtyard, mentioned by some local history writers in the past century. (M.T.)
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