Built in 1540 for Licentiate Don Sancho Díaz de Leguizamón, Mayor of the Court and member of His Majesty's Council, at the beginning of the 17th century it was acquired by Don Diego Sarmiento de Acuña, ambassador and Count of Gondomar. In 1612, he commissioned the completion of the building under the supervision of the architect Francisco de Praves, while also completing the neighboring temple of San Benito "el viejo," which his family patronized. Hence, we see the coat of arms of the Count of Gondomar on the balcony of the main entrance and on the gable of the adjacent church of San Benito el Viejo, which displays a monumental shield.

The name Casa del Sol comes from the figure that crowns the façade. Inside the palace, the owner assembled one of the most important libraries in the kingdom.

Owned by the State, it is affiliated with the National Museum Colegio de San Gregorio.