The combination formed by the courtyard and the galleries that surround it covers an immense area whose dimensions are about 90 metres long and 72 metres in width. The northern part of the courtyard is paved with flagstones while the rest of the floor is almost entirely composed of white marble slabs. Near its centre is an horizontal sundial, bearing an inscription in naskhi engraved on the marble dating from 1258 AH (which corresponds to the year 1843) and which is accessed by a little staircase; it determines the time of prayers. The rainwater collector or impluvium, probably the work of the Muradid Bey Mohamed Bey al-Mouradi (1686–1696), is an ingenious system that ensures the capture (with the slightly sloping surface of the courtyard) then filtering stormwater at a central basin furnished with horseshoe arches sculpted in white marble. Freed from its impurities, the water flows into an underground cistern supported by seven-metre-high pillars. In the courtyard there are also several water wells some of which are placed side by side. Their edges, obtained from the lower parts of ancient cored columns, support the string grooves back the buckets.