A hilltop fortress on the Guadiana near Ciudad Real, still half-built when Alfonso VIII lost the great battle of 1195 beneath its walls.
Alarcos stands on a low hill above the river Guadiana near modern Ciudad Real, on what in the 12th century was the exposed southern frontier of Castile. Alfonso VIII was fortifying it as a frontier stronghold when the Almohads struck.
The castle was still unfinished on the day of the battle in July 1195, and its incomplete walls could not shelter the broken Castilian army. After the defeat the Almohads took the site, and it never regained importance.
The hill of Alarcos is now an archaeological park, with the remains of the medieval castle and church and, beneath them, an older Iberian settlement. The open ground below the walls is the battlefield of 1195.
Excavations have made Alarcos one of the better-studied frontier sites of central Iberia, preserving the memory of the day the Castilian frontier collapsed.