These gates served as an entrance to the Friedrichsburg fort (the original fort was built here in 1627). In 1657 the Great Elector Friedrich Wilhelm ordered the addition of the new fort to the city fortification ramparts. The fort was designed by the court mathematician Christian Otter and had four bastions, each of which had a special name: Emerald, Pearl, Ruby and Diamond. This was in accordance with the colours of the coats of arms of the three medieval cities Kneiphof, Löbenicht and Altstadt, out of which later appeared Königsberg, whilst the name Diamond corresponded to the Castle Königsberg as a symbol of power. Here in May 1697 the young Russian tsar, Peter I, studied the art of projectile throwing and firework manufacture.
Preserved until the present day, the gates were attached to the fort from the city side in 1852-1858. The gates façade was designed by the Chief Privy Councillor of construction Friedrich August Stüler. The gates make a harmonious impression due to their balanced vertical and horizontal parts. The high quality of the laying of the red bricks attracts great attention as well. The gates had four round towers, two casemates and an entry arch with double wooden doors. From the side of the city the façade was decorated with the Prussia’s coat of arms – a black eagle – and a Gothic inscription “Fort Friedrichsburg”.
After the destruction of the fort in 1916 auxiliary railway tracks were constructed over its former position, but by decision of the then mayor of the city, Siegfried Körte, the gates were preserved as an architectural monument.
After the war the badly damaged gates were standing in the center of the city without any significant use. In 2007 the gates were given over to the control of the Museum of the World Ocean and restored. Today you can see a wonderful exposition “Ship’s Revival” there.