From the Back of the Book:
Have your players wandered off the beaten path yet again? Didn't have time to map out that castle? Just open Seven Strongholds to find forts, castles, and other well-fortified locations, fully detailed and ready for insertion into your game world.
The Barrows: A concrete bunker allows a determined troop of gnomes to hold at bay the misshapen monsters of the subterranean world, intent on breaking through to the surface.
Castle Briar: An elven warlord protects his living castle from jealous rivals.
Gloom Keep: Under a sunless sky, grim-faced humans protect their senile, maddened deity from the world.
Old Mound Fort: An iron-age ditch and rampart fort, refurbished by halfling adventurers, offers a way station for treasure-hungry dungeon explorers.
Steelface Point: An imposing dwarven fortress protects the mouth of a mountain pass from the orcish horde and its war machines.
The Perch: Keen-eyed bird-men zealously guard their domed lair, from which they oppress the area's population of "walkers" - their contemptuous term for flightless humanoids.
Uthront Fort: Ambitious half-orcs occupy a newly-built motte-and-bailey castle as an early stage of their effort to mold the local humanoid raiders into a mighty and unified army.
Like all Penumbra products, Seven Strongholds gives you material adaptable to any fantasy campaign, whether it be a published setting or a world of your own creation.