The combination of Sicilian and Arabic influences in Malta's Medieval architecture was set by climacte and lifestyle rather than architectural philosophy or design. This may be seen in the typical, cube-shaped houses that survive in Malta from medieval times to the present day. Built on two floors, such houses face south for maximum sun exposure, with courtyard loggias to trap the winter sun but shade the rooms from the summer's heat.
Under the Arabs, Malta benefited from an advanced culture where poetry, music and mathematics flourished. However, Ibn Haldun tells us that in 1249, Frederick II 'chased out' the Muslims who lived in Malta. The Arabs must have taken their masons and craftsmen with them, sinc after they left, few, if any, Maltese had the skills to build free-standing structures. Indeed, wherever there were caves, or the rock was easy to carve out, the people used caves and catacombs as churches.
The best known of these simple-cut catacomb-churches are those of St Agatha and St Paul in Rabat. Documents from Norman times speak of crypta which means a rock-cut church, like the ones used in the 13th century when Sicilian Basilian monks brought Christianity to Malta and settled in these caves that were located in remote parts of the island. Meanwhile many hermits lived in deserted rock-cut tombs. There are twenty rock-cut churches all over Malta and Gozo, some having built facades leading into cave-like interiors. These fascinating churches were constructed while Malta was under the influence of the Byzantine rites. In fact, they are dedicated to Byzantine saints such as Saint Cyril, Saint Basil, Saint Michael and Saint George.
The simple, one-room churches at Tas-Silġ and San Pawl Milqi are the earliest built after the Arabs left. Although churches started to have a semi-circular apse and half-dome, the roofing system remained that of the Arabs. Unlike Sicily, Malta did not have plentiful trees to make beams. So the Syrian system of arches supporting long stone roofing slabs was perfect for Malta, producing churches that were quite unique to our islands. The external walls would be plain, with few or no openings. Often, the only ornamentation were the rain-spouts and the pointed doorway which were at times changed in later periods, ruining the stonework in the process.
More sophisticated churches also started to be built; the Annunciation of the Virgin in Ħal Millieri being one of the best preserved examples. Along with others, like San Bażilju in Mqabba, and Santa Marija ta' Bir Miftuħ, these chapels are cube-shaped, single-room buildings with a slightly pointed roof supported by pointed arches beneath. The bell-cots above the churches were not part of the medieval structure but were added later and were sometimes too large for the simple structures beneath. The very plain exteriors of these medieval churches often hid brightly painted interiors. This style continued to be use into a later period, as St. John's Cathedral, with its enormous ribbed vault, echoes these little churches much more than it resembles the great Renaissance churches of Rome.
By the 15th Century, the Maltese had emerged from their Dark Age and become good builders. The pointed arches gradually became rounded barrel-vaults. The side pilasters supporting the arches disappear or become only decorative. The church of St. Catherine, the parish church of Żejtun, was built around 1492 and was the finest church to date with an unusually advanced roof.
Whole communities throughout the Middle Ages lived in caves, and to this day some farmhouses beneath Dingli Cliffs are still partly made out of caves. The caves were either man-made or were natural caves. The largest cave settlement was Għar Il-Kbir in Dingli, which, translated, means the Big Cave. Located between Buskett Gardens and Dingli Cliffs, this complex housed approximately 27 families, each family's allotment being defined by rubble walls inside the cave which included shelves cut into the walls, cooking areas and animal pens. This cave was inhabited until as recently as 1835 when the inhabitants were resettled against their will in Siġġiewi since the cave was considered unhealthy.
In medieval Malta, more sophisticated stately homes in Mdina and Birgu resembled simpler vernacular houses but were decorated with sculpted trimmings of simple geometric patterns. Dated to between the 14th and 15th centuries, some survive in Mdina, including the palazzi of Santa Sofia, Gatto Murina, Inguanez and Falzon. Their style is known as Castiglione style because they show some Siculo-Norman influences, particularly in their twin-arched windows which mark the climax of medieval architecture in Malta.
A.T. Luttrell, Approaches to Medieval Malta in Medieval Malta – Studies on Malta before the Knights
Leonard Mahoney, 5000 Years of Architecture in Malta
Leonard Mahoney, A History of Maltese Architecture