Old castle of Manzanares el Real

The Old Castle of Manzanares el Real is the ruin of a medieval fortress perched on a small hill above the Manzanares River, at the southern edge of La Pedriza in the Sierra de Guadarrama. Locals know it as Plaza de Armas, a name that hints at its original role as the defensive stronghold of the Mendoza family, long before the town's famous Renaissance castle was ever built nearby.

Where does the Old Castle come from?

Nobody knows exactly when the fortress was built, but it certainly predates 1475, the year the Mendoza family began constructing their new, palace-style castle a short distance away. Historians still debate who commissioned the original structure: some point to King Alfonso XI, others to Diego Hurtado de Mendoza, Admiral of Castile. Neither claim has been definitively settled.

The turning point for this land came on 14 October 1383, when King John I of Castile, seeking to end long-running border disputes between Madrid and Segovia, granted half of the lordship of Real de Manzanares to Pedro González de Mendoza. That grant marked the beginning of a lasting Mendoza presence here, a presence the Old Castle physically embodies.

What did the fortress look like?

The castle followed a rectangular plan, with cylindrical towers on three corners and a larger keep on the fourth. Builders used the Mudéjar technique typical of the region: walls of dressed granite with brick used for detailing, particularly around openings. This combination of stone and brick was a hallmark of Castilian military architecture of the period.

Why did it fall into ruin?

The fortress's fate was sealed by the Mendoza family's own rise. In the last third of the 15th century, with their wealth and standing greatly increased, they chose to build a far grander, more prestigious residence nearby — today's New Castle. The old fortress was deliberately dismantled and abandoned: partly to reuse its stone for the new construction, and partly to deny it as a foothold to any rivals of the family, given how close the two buildings stood to each other.

What can visitors see today?

What remains are sections of the old perimeter walls, now enclosed within a landscaped, fenced area. It is no longer a castle in any functional sense, but a tangible trace of the earlier, purely defensive chapter in the history of Manzanares el Real — a fitting complement to a visit to the much better-preserved New Castle, which stands just a few hundred metres away. Seeing both sites together makes it easy to trace how the Mendoza family's ambitions shifted over time, from a bare defensive stronghold to a palatial residence built to impress.

Manzanares el Real sits on the edge of the Santillana reservoir, at the gateway to La Pedriza, one of the most visited corners of the Sierra de Guadarrama and a favourite of hikers and climbers coming out from Madrid.

Frequently Asked Questions

What is the difference between the Old Castle and the New Castle of Manzanares el Real? The Old Castle is the earlier, medieval defensive stronghold of the Mendoza family, today preserved only as a ruin. The New Castle, begun in 1475, was built by the same family as a grand palace residence and survives in far better condition.

Who built the Old Castle? The founder and exact date are uncertain — either King Alfonso XI or Diego Hurtado de Mendoza, Admiral of Castile, are credited. What is documented is that the fortress already existed before 1383, when the surrounding lands passed to the Mendoza family.

What did the original castle look like? It had a rectangular layout with cylindrical towers on three corners and a larger keep on the fourth, built in the Mudéjar style using granite masonry with brick detailing.

Why is the castle a ruin today? The Mendoza family dismantled and abandoned it after building the New Castle in the late 15th century, both to salvage building material and to prevent it from being used against them given its proximity to their new residence.