Seonamposa (Southwestern Sentry Station) was used by troops to send warning signals to other troops around the fortress. It is located above Seonamammun, the Southwestern Secret Gate.
If the area came under attack, troops from this location would send warning signals. These warnings signals were sent to the rest of the fortress by waving a flag or by firing a cannon.
This beautifully painted structure is about 3.9 meters (12.7 feet) wide and has two panel wooden doors on all four sides.