The "forties square" took its name from the people who participated in traditional meetings in Hz. Fatima’s house. These meetings were related with the religious education of Bektashis.

On the picture: A pendentive, adorned with a muqarnas-style decoration.

A ‘pendentive’ is a constructive device permitting the placing of a circular dome over a square room (or an elliptical dome over a rectangular room). The pendentives, which are triangular segments of a sphere, taper to points at the bottom and spread at the top to establish the continuous circular or elliptical base needed for the dome. In masonry the pendentives thus receive the weight of the dome, concentrating it at the four corners where it can be received by the piers beneath. The pendentive was introduced by the Romans (around 200 AD) and fully used by the Byzantines.

Muqarnas is a stalactite-like decoration initiated in Anatolia by the Seljuk (in the 11th – 12th century). They imported it from Iran. Later on it continued to be used in the late-Seljuk architecture of the Beyliks (14th century) and by the Ottomans up to the 19th century.

Correspondent: J.M.Criel, Antwerpen.
Source: (amongst others) Wikipedia.