Castro Marim castle is an impressively intact medieval border fortress to visit and was home to the Order of Christ. Guarding the frontier with Spain the castle was heavily restored throughout the 1960s and 70s. It is difficult to appreciate the scale of the walls from the outside as there are so many trees growing up against them. The hillside opposite has the Fort of St Sebastian on it and in the seventeenth century the two were linked by walls, now gone.
Visiting Castro Marim Castle
Castro Marim is a very easy castle to visit, although parking was not immediately obvious. The castle can be seen from quite a distance, which is rather the point, but we had to park on a side street in the town. The access ramp had plenty of Templar banners on it and the entrance fee was minimal.
Inside there was a small museum with a history of the Order of Christ, in English. There were a few information boards inside the castle but it could do with a lot more development inside. I think a lot of the temporary structures in the courtyard were remnants of the annual medieval faire, that Covid has put a stop to.
My Experience
Our visit to Castro Marim was as part of a ten day road trip through southern Portugal, detailed in my blog here and was the tenth castle of the eleven that we saw. We drove from Tarifa and it was maybe 45 minutes including a diversion to cross the bridge into Spain!
This is a large medieval structure, originally developed by the Templars and then, after some deft political manoeuvring by the Portugese king, the Order of Christ. He created this military order to take over the Templars properties (and probably personnel too) so they didn’t go to the Pope when he dissolved the order at the request of the perfidious French king, Philip II. The castle became very wealthy and was an important border fortification, both against the Moors and after 1492, against the Spanish.
In the seventeenth century a more modern defensive structure, the fort of San Sebastian, was built on the adjoining hill but this wasn’t open to the public. We paid the small entry fee and went into the castle museum which had a good history of the place before climbing the steps to the walls and doing a circuit of the castle. We were actually able to see the Guadiana Bridge in the distance too. The walls were quite uninspiring though, there were no real towers or bastions that we could get to.
The keep is a large and imposing building inside the walls but other than walking around the courtyard we couldn’t go into the towers or on the walls. The inside seems to have lots of temporary structures ready for the medieval fair that is held in the castle every year but obviously covid has devastated that source of revenue.
Castro Marim Castle Photo Gallery
Fort of San Sebastian 
Fort of San Sebastian 
Looking towards Castro Marim entrance, from the museum 
Panoramic view across to San Sebastian Fort 
Castro Marim keep 
The Guadiana Bridge 
Castro Marim keep 
View towards Fort St Sebastian 
Very useful device! 
One of the village ladies made this garden on the bank surrounding the castle
History
Castro Marim Castle lies in the village with the same name in the province of Algarve in Portugal. It is locally known as Castelo de Castro Marim.
Castro Marim is a peculiar village; it is situated between two hilltops and on each of the hilltops stands a robust fortification; Castro Marim Castle and Fort São Sebastião. The border with Spain; the Guadiana river, is just 2 kilometers to the east.
Castro Marim Castle has a rectangular shape with 4 round corner towers and 2 entrances. It is probably, in origin, a castle built by the Moors to protect the Portuguese coast. But the village was already an important port during Phoenician and Roman times. The Romans called it Baesuris.
In 1242 the castle was taken from the Moors by Don Paio Peres Correia during the reign of King Alfonso III. After the Christians had conquered Castro Marim they rebuilt and reinforced the castle. New battlements were built around the hilltop on which the castle stood. This was done to protect this strategic position against attacks coming out of the east; from Castile, and from Moorish attacks coming from North Africa. This created a castle within a castle situation. The inner castle became known as ‘Cacela Velha’ or the ‘Old Castle’.
In 1319 King Dinis ordered another reinforcement of the castle’s fortifications. He also made Castro Marim Castle the head quarters of the Order of Christ, created to substitute the Templar Order. Later King Fernando also restored the entire fortification. In 1504 another restoration followed, this time ordered by King Manuel.
In 1641 King João IV ordered the construction of Fort São Sebastião on the opposite hilltop to the south. Castro Marim Castle was again reconstructed and the two bulwarks were connected with walls that also enclosed the village between them.
Nowadays both bulwarks lie in ruins and the connecting walls have largely disappeared. This is a nice example of border fortification architecture over the centuries. The castle can be visited for a small entrance fee. The fort is freely accessible.
References
The history above is copied from the excellent castles.nl site here.
There is also a comprehensive right up on the Wikipedia page here.