The Sherif Halil Pasha Mosque, more commonly known as the Tombul Mosque, located in Shumen, is the largest mosque in Bulgaria and one of the largest in the Balkans.
Build between 1740 and 1744, the mosque was initially located in the north-eastern Bulgarian (then Ottoman) town's centre, but is now in Shumen's south-west parts as the town centre moved as a result of the enlargement of the town. The mosque's name comes from the shape of its dome.
The mosque's complex consists of a main edifice (a prayer hall), a yard and a twelve-room extension (a boarding house of the madrasa). The main edifice is in its fundamental part a square, then becomes an octagon passing to a circle in the middle part, and is topped by a spherical dome that is 25 m above ground. The interior has mural paintings of vegetable life and geometric figures and inscriptions of Arabic, phrases from the Qur'an. The yard is known for the arches in front of the twelve rooms that surround it and the minaret is 40 m high.
References:The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.