The castle stands in the center of town and houses the current Archivo General de Simancas.

In the 15th century the House of Enríquez constructed a new fortification on top of the existing ruins, restored the Moorish walls, and added a chapel.

The new castle was seized by the Spanish Crown during the reign of the Catholic Monarchs and turned into a prison.

The castle's foundation, walls, battlements, gates, and bridges all date back to the late 15th century, mostly attributed from 1467 to 1480.

[1] The current archive housed within the castle has been protected with fireproofing measures, and the 15th-century chapel built by the Enríquez has been restored.