The Big Sea Gate is located in the Old Town of Tallinn, not far from the seaport. In 1265, the Danish Queen Margarita ordered to bring the border of the city fortifications from the north side of the Old Town to Tolly Street. Simultaneously with the construction of the city wall, the first gates were built. In the XIV century, they were rebuilt and called the Great Sea Gate. Their main purpose is to protect Tallinn from the sea. In addition, they served as the "calling card" of the city. All overseas guests of the capital of Estonia entered the city through the Great Sea Gate. On both sides of the gate defensive towers were erected. In 1529, one of them was dismantled, and in its place a thick-walled gun tower Thick Margarita was built, next to which there was a passage and a quadrangular tower with a lowering grate. This tower has not retained its original appearance to this day, after a strong fire that occurred in 1757, it was completely rebuilt. On the outside, the gates are decorated with a dolomite plate with a carved small coat of arms of Tallinn. The heraldic emblem is made by the sculptor Herth Kenning, has the appearance of a battle shield with a cross supported by griffins, the coat of arms crowned with a knight's helmet on top. On the inside of the gate, in a niche, is a wooden crucifix dating from the 19th century. Over time, the Big Sea Gate lost its defensive significance and became one of the sights of Tallinn, and the Estonian Maritime Museum is located in the tower of Tolstaya Margarita.