The Holy Trinity Cathedral is a Bulgarian Orthodox cathedral in the city of Ruse on the Danube river. It stands next to the modern day opera house. Built beneath the ground in 1632, it is the oldest church in the city and was constructed during the period of Ottoman occupation. As it keeps the holy relics of a number of saints, Ruse's cathedral is often visited by pilgrims. Its rich history and underground interior also pose an interest for tourists, making it one of the main attractions of the city.
It is a three-nave pseudo-basilica that is 31.20 m long and 15.60 m wide. Two rows of seven columns separate the naves. It was dug four and a half meters below the level of the yard due to the requirements of Ottoman authorities. The remains of catacombs, possibly dating back to the fifth century, are located in the southwest corner of the temple. During Ottoman rule, it was easier to issue permission for the construction of a new church at the location of an older temple. The Christians of Ruse presumably used the old catacomb to build the church.
The hexagonal belfry is 19 m high and was built with stones from the fortification facilities around the Ruschuk fortress, demolished by decision of the Berlin Congress from July 1878. There are five bells in the belfry. In the cathedral's narthex are the graves of four bishops of the Dorostolo-Cherven diocese: Grigoriy, Valisiy, Mihail, and Sofroniy.
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.