The Gate can be visited
Town Fortification Stralsund-Knieper Gate

The Kniepertor in Stralsund is a structure of the former city fortifications. As one of the preserved land gates, it is a component of the UNESCO World Heritage Site "Historic Old Towns of Stralsund and Wismar".
History+
First documented in 1293, the Kniepertor was named after a burgher family of the 13th century. In the 15th century, the brick-built gate underwent structural changes that shaped its current appearance. Although demolition was discussed in the 1860s, it was decided in 1870 to remove only adjacent buildings and the outer gate to facilitate increasing traffic.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: https://commons.wikimedia.org/wiki/File:Stralsund_Kniepertor_Front.jpg
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: 54.3174, 13.0897