From humble beginnings, the hill was raised during various periods of history up to 9 meters above the surrounding landscape in the 11th century. Ada van Holland used the keep as a residence until her father died in 1203 and she was captured by her uncle. In the same year the previous stone building was rebuilt after an attack on the castle, with tuff stone, and after Ada's removal, in 1204 it was attacked again and rebuilt with brick. Later in the 13th century the building was considered antiquated, since more and more townspeople and houses were built around the base of the hill, making defenses impossible without destroying most of the city. The old "interior keep" that had been built against the interior walls was slowly dismantled and reused for city construction.
Symbol of Leiden
As the city of Leiden grew around it in the 13th and 14th centuries, the ruined castle lost its military function. The location became a romantic patriotic symbol after the Siege of Leiden in 1574, as historians recalled the earlier sieges of Leiden: Ada in 1203 and the siege in 1420. The stained-glass windows number 25 & 26 in the Janskerk designed by the Leiden artist and councilman Isaac van Swanenburg glorifies this history in 1601 by commemorating the latest siege with a comparison to the "historical" story of the Siege ofSamaria. The city of Samaria is portrayed with a watch tower much like the Leidse Burcht.
Public park
In 1651 the city bought the premises to make it into a water tower for public use. A system of waterpipes leading to squares in the city is still intact. In this period a new portal on the keep wall was designed in 1662 with heraldric symbols by Rombout Verhulst, denoting the leading families of the city. There are two other gates to the Burcht, one at the base of the hill with wrought iron heraldric weapons, built in 1653, and one on the south side of the complex, which itself forms a gateway to the park. In this Southern gateway a poem in Latin was used for centuries to teach the rudiments of grammar to Leiden students. A memorial plaque was placed in 1999 with the modern translation in Dutch.
