Seonam Ammun, Seonamposa

The Fortress had several secret gates here and there, which permitted people to move around unnoticed by the enemies. The Seonamammun was one of them.
Ammun is a military facility set up in a deep and secluded spot, through which war supplies would be secretly carried into or taken out from a castle. In a case of emergency, the gate should be closed and covered up with stones and earth so that enemies could not find it.

As the Seonamammun was located close the Seonam Gangnu, the command post, and the Yongdogil, which was a road used to move military provisions, the gate was considered to be among the especially important among secret gates. This is why the Seonam Gangnu has a building attached to it unlike other such gates
Yongdo Road is seen in a movie entitled Man of the King.

Normally, the secret gates did not have buildings above them, as they were meant to be hidden from the enemies. But the Seonamammun had a structure called the Posa, which was used to observe the enemy and relay signals. It was more of a guard post, and did not have offensive facilities.