Hidden Fortress is a three player (two vs. one) skirmish map in Command & Conquer: Red Alert 3.
The map is set on a Floating Fortress, featuring two bases on a small island at one end, and the third on the main island at the other end. The two bases at the south-west are very close to each other.
Around the map there are six Observation Posts, five on the main island, and one behind where the two other bases are. There are three other islands on the map, two with an ore mine and an Oil derrick and a third with a Tech Airport. The island with the the two bases also has two oil derricks and two Dry Docks. The main landmass has two Hospitals, two Garages and two Veteran Academies. There are four ore mines near the main entrance to the island, and two pairs of them near the base there.