Concepción Castle, locally known as Castillo de la Concepción, lies on a hill in the center of the city of Cartagena in the province of Murcia in Spain.
Cartagena was founded in the 3rd century BC by the Carthaginian general Hasdrubal the Fair. It was built at the site of a natural harbour. As far back as the 16th century it was one of the most important naval ports of Spain. During the 18th century the city was heavily fortified which resulted in the building of lots of forts and batteries on the hills and mountains around the harbour. At present the city is still the headquarters and main military port, also for submarines, of the Spanish Navy and it possesses a large military shipyard.
Ancient Cartagena was built on a small peninsula surrounded by five hills. On the highest hill probably stood a temple dedicated to the god Asclepius. During the 12th century the Kingdom of Murcia was ruled by the Almohads. They built an alcazaba; a Muslim palace-fortress, on this hill. That fortification was mainly built out of rammed earth, a technique also known as tapial.
In 1245 the city was taken by the troops of Alfonso X of Castile. Probably in the 2nd half of the 13th century construction of the large keep started. It was built reusing stones from local Roman ruins and Roman gravestones. During this time Alfonso also founded the Order of Santa Maria of Spain in Cartagena, which was meant to fight naval battles against the Muslims. The Order however failed to win battles and was dissolved. This, and the fact that the Castilians had a big difficulty in repopulating the abandoned Muslim town with Christians, led to the castle not being finished.
What remained of Concepción Castle was still the main defensive element of the city during the 16th and 17th century. At the end of the 18th century the castle lost its military importance and it was even partially demolished in the beginning of the 19th century.
In the 1920's the castle area was transformed into a city park. The keep now houses a small museum.
At present Concepción Castle can be visited for a fee. Because large parts were demolished it is hard to get a feel of how the castle might have looked. But the museum is nice and the views over the city too.