From OpenStreetMap Wiki
|barrier = sally_port|
|A secure, controlled entryway to a fortification or prison.|
|Used on these elements|
|Tools for this tag|
is a secure, controlled entryway to a fortification or prison. The entrance is usually protected by some means, such as a fixed wall on the outside, parallel to the door—which must be circumvented to enter and prevents direct enemy fire from a distance. It may include two sets of doors that can be barred independently to further delay enemy penetration.
How to map
Simply place a node on a place where sally port is located and tag it barrier=sally_port.
suggested by User:Chrisana13