Sultan Bayezid II Mosque and Complex The Sultan Bayezid II Mosque and Complex is a remarkable feat of Ottoman architecture, featuring a mosque, guesthouses, a madrasah, a hospital, and a soup kitchen-cellar for food storage. At the heart of the complex is the darussifa, or hospital, and madrasa, which served as a medical school. Other units were constructed to complement the hospital's services in social, cultural, religious, and financial aspects, and the Bayezid Khan Bridge over the Tunca River connected the complex with the city. Construction began in 1484 under the orders of Sultan Bayezid II, and while there are conflicting claims as to who the architect was, most experts credit Hayrettin with its design. Hayrettin is renowned for constructing several essential structures during Bayezid II's reign. Darüşşifa, the complex's central hospital, is among the most significant early modern-period Islamic and European attempts to establish a "central system." It features a hexagonal treatment area covered by a large dome at its center, with medical units located around two courtyards connected to each other. This arrangement enabled optimal medical service provision and played a vital role in providing protective services. The smallpox vaccine applied to children at Darüşşifa was taken to England by Lady Mary Wortley Montagu, who visited the Ottoman Empire and began applying the vaccine there as well. The Sultan Bayezid II Complex is widely regarded as a pioneering example of modern hospital architecture, incorporating advanced systems for ventilation, lighting, and sound-proofing, as well as a polyclinic section, inpatient facilities, laboratory, and storage rooms. Located at the center of the complex is the mosque, which boasts a unique dome measuring 20.55 meters in diameter, distinguished from other single-domed mosques by the absence of any foot-column system. Instead, the dome is placed directly on top of the walls, creating a serene and classical internal space. The mahfil, or gathering place for sovereignty, is situated on large marble columns to the right of the mihrab, while intricate woodworking on the interior doors and windows showcases meticulous attention to detail. In recognition of its architectural significance, the Sultan Bayezid II Mosque and Complex was added to UNESCO's Tentative List in 2016.