Kitâbe (building inscription) above the northern window of the Seyit Battal Gazi Türbesi (mausoleum), mentioning Mihaloğlu Ali Bey as initiator of the reshaping of the exterior in 849 (Islamic calendar), which is 1464/65 AD. The inscription has five lines, and is written in sülüs script.
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.
Correspondent: J.M.Criel, Antwerpen.
Sources: ‘SEYİTGAZİ KÜLLİYESİ’ - Doç. Dr. Canan PARLA (Anadolu Üniversitesi) & Wikipedia .