Helsinki Cathedral is a distinct landmark in the scenery of central Helsinki, with a tall green dome surrounded by four smaller domes. It was built in 1830–1852 in neoclassical style to replace an earlier church from 1727. The cathedral was designed by Carl Ludvig Engel, to form the climax of the whole Senate Square laid out by Engel, surrounded by a number of buildings all designed by him.
Today the cathedral is one of the most popular tourist attractions in Helsinki. Annually more than 350,000 people visit the church, some of them to attend religious events, but most as tourists. The church is in regular use for both worship services and special events such as weddings.
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.