Cemaleddin Ferruh Darülhadisi (Taş Mosque) The Cemaleddin Ferruh Darülhadisi Mosque in Çankırı is considered the most significant structure from the Seljuk Period. The mosque and hospital were constructed in 1235 by Çankırı Atabeyi (Governor) Cemalettin Ferruh during the reign of the Anatolian Seljuk Ruler, Alaeddin Keykubat I. Unfortunately, the hospital, which was built with rubble stone, was destroyed over time. In 1242, Cemalettin Ferruh had both a mosque and Dâr-ûl Hadis (a school for the study of Hadiths) built. The mosque is known locally as Taş Mescit for its unique architecture, as well as two remarkable pieces of stone artwork. The first is a "Medical Symbol," featuring two entwined snakes, which can be seen as a figurative stone work on the mosque, and as a sculpture in the Çankırı Museum. The second piece, also exhibited in the museum, depicts a snake figure entwined in a cup, which is used as a "Pharmacy Symbol" today. The structure also contains a mausoleum with two burial chambers. The north façade burial chamber houses a sarcophagus, while the two-section room on the east façade contains five cists. It is believed that mummified corpses known as cadis were used during this time period, with one of these coffins thought to belong to Cemalettin Ferruh himself, the founder of the work. His coffin was placed above what many consider the main area or the central chamber. The building still serves as a mosque and was used as a Mevlevihane (a house for practicing Sufism) for many years until the establishment of the Republic.