The Burgtor can be visited
Lübeck City Fortification-Burgtor

The Burgtor in Lübeck is a structure of the former city fortifications and, alongside the Holstentor, the only remaining one of what were once four city gates. It is located in the north of the Hanseatic city.
History+
The current Burgtor was built in 1444 by city architect Nicolas Peck, replacing an older Romanesque gate. It owes its name to the former Lübeck Castle, which was converted into the Burgkloster in 1227. In the 19th century, there were considerations to demolish the gate to create building space. However, the city council unanimously rejected this and instead decided to expand the passages. Thus, additional passages were created in 1850 and 1875, with a final one added in the late 1920s, so that the gate now has four passages. Originally, the preserved gate was the inner part of a complex fortification system with three gates situated one behind the other, which began as a double gate system in the 15th century and was supplemented by a third gate in 1622. This expansion was due to the fact that this was the only land access from the north to Lübeck's city center. In 1806, French troops entered the city through the Burgtor during the Battle of Lübeck, which is commemorated by a plaque.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Rainer Gindele
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 53.8740, 10.6911