Ismail Fakirullah Tomb & Light Refraction Mechanism The Ismail Fakirullah Tomb along with two other buildings connected to the Light Refraction Mechanism are located in the Aydinlar (Tillo) District of Siirt. Following the death of Ismail Fakirullah, his disciple Ibrahim Hakkı constructed the tomb during the 18th century. The tombstones date back to the 19th century. Unfortunately, due to improper restoration carried out in 1963, some of the tomb’s original features were lost. The Ismail Fakirullah Tomb consists of two chambers and a corridor, topped by one large and two smaller domes, as well as an adjacent tower. Its structure follows a square plan crowned with a dome that is supported by squinches. Each facade of the building includes two rows of windows. The windows on the lower level have straight lintels with curved arch pediments, whereas the upper-level windows are designed with pointed arch openings. The tomb’s entrance section is square and covered by a dome, which leads into the main chamber, also square in shape. The interior walls are plain and undecorated, housing multiple tombs in addition to that of Ismail Fakirullah. Nearby stands an octagonal tower reaching a height of 10 meters. The tomb, tower, and light refraction mechanism hold great importance together with the Kalet'ul Üstad—a wall constructed from rubble and undressed stones of various sizes without any mortar—situated on a hill that overlooks the Botan Valley, about 3-4 kilometers east of Tillo. Every year on March 21st (Nevruz – which was added to the Representative List of the Intangible Cultural Heritage of Humanity in 2009) and September 23rd, the first rays of the rising sun are precisely reflected by a specially embedded reflector in Ismail Fakirullah's tower. Through this mechanism, the light illuminates the grave of Ismail Fakirullah. The illumination begins from the lower left part of the grave and lasts for approximately 6 minutes. During the first 3 minutes, the entire grave is fully lit by the reflected sunlight, and in the remaining 3 minutes, the light gradually fades away, moving in the opposite direction from the upper part of the grave. The Ismail Fakirullah Tomb and its light refraction mechanism represent a deep spiritual and cultural legacy that has been preserved over centuries. This mechanism conveys Sufi beliefs by emphasizing Ismail Fakirullah’s grave on March 21st, which is regarded as the beginning of a new year by many communities and peoples in the region. The Ismail Fakirullah Tomb & Its Light Refraction Mechanism was included in the UNESCO Tentative List in 2015.