On the picture: Close-up of the border(s) of the ‘mihrab’ (prayer niche, which indicates the direction of Mecca).
The niche is completely executed in glazed tiles. The right border shows elegant calligraphy in which two scripts were used: kufic (in yellow) and sülüs (in white). The middle border has a muqarnas (stalactite) decoration, similar to stonecraft work. The border to its left is inspired on the looks of the ‘kündekari’ woodwork technique.
This is an example of the Islamic passion for relating areas and objects of disparate size and purpose through their decoration.

Kufic is the oldest calligraphic form of the various Arabic scripts and consists of a modified form of the old Nabataean script. Kufic developed around the end of the 7th century in Kufa (Iraq). Until about the 11th century it was the main script used to copy Kurans.

Sülüs (from Arabic: ثلث‎ ṯuluṯ "one-third"), also referred to as ‘thuluth’, is a script variety of Islamic calligraphy invented in Persia, which made its first appearance in the 11th century AD. The straight angular forms of the older Kufic script were replaced in the new script by curved and oblique lines. In Sülüs, one-third of each letter slopes, from which the name (meaning "a third" in Arabic) comes. It is a large and elegant, cursive script, used in medieval times on mosque decorations.

In the ‘kündekari’ technique pieces of wood of different sizes are worked separately, and then assembled (like a big jigsaw puzzle), without using any glue, split pin or nail. The technique was used in Egypt, Syria and Anatolia from the 11th century on, and became a major art form in Seljuk and late-Seljuk times (13th-15th century).

Correspondent: J.M.Criel, Antwerpen.
Sources: ‘Vakıf Abideler ve eski Eserler’ - Vakıflar Genel Müdürlüğü III, Ankara 1983 ; Wikipedia
& ‘Islamic Architecture: Ottoman Turkey’ (Godfrey Goodwin) – London 1977 .