In the city of Las Palmas de Gran Canaria, the capital of the province of Las Palmas, in the north of the island of Gran Canaria, Spain's Canary Islands, the Castle of La Luz or Fortress of Las Isletas is situated on Juan Rejón Street in the neighbourhood of La Isleta next to the Port of La Luz.

The third Governor, Alonso Fajardo, gave the order for its construction in 1494, when the island of Gran Canaria was included in the Crown of Castile, to act as a defensive castle.

The stronghold was once built on a reef and cut off from the rest of the world during high tide, but as the city has grown, it has been left on dry land and is now more than 150 metres from the sea.

When the Canary Islands were first conquered in 1478, Captain Juan Rejón constructed a wooden fort on top of which the current structure was placed. In accordance with the requirements for defence, it was constructed in stages. First, the medieval-style quadrangular tower called the Alonso Fajardo Tower Then, around around 1515, a perimeter defensive bastion was built. A few years later, it was expanded. It underwent reconstructed in 1553 after the fire of 1599, which was brought on by the Dutch armada led by Pieter van der Does. The outside building that can be seen today was built towards the end of the 17th century.

Up until the nineteenth century, it still had a protective purpose. It was the first defensive structure on the island, and the Castillo de Mata, Castillo de San Cristóbal, and Castillo de San Francisco, which are all a part of Las Palmas de Gran Canaria's urban wall, were built after it.

After being abandoned for many years, it underwent restoration in 1969, adding additional features such an outer moat and new arches, and was then utilised as a cultural centre.

In 1998, a new repair plan for the castle that took into account its historical development and preserved many of its original components was revealed.

The Castillo de la Luz, which was designated a Historic Artistic Monument in 1941, is a part of the Spanish Historical Heritage due to its significant testimony of the defensive architecture of Las Palmas de Gran Canaria, which is located next to the port and was a necessary passage for the Spanish fleets returning from America with their valuable cargoes that were under threat from piracy.

The Martn Chirino Foundation of Art and Thought has had its administrative offices in a new annex building, with a representation of the works from the private collection of the Canarian sculptor Martn Chirino inside, since its opening in 2015 after being renovated with the architectural project by Nieto and Sobejano to create a museum space.

The outside moat that was erected to the Castillo de la Luz a century earlier gave it a square floor plan and a drawbridge for access. It has a sentry box in the northwest corner, two circular towers, one to the northeast and the other to the southwest. A doorway with a semicircular arch provides access. A cistern is located inside. Three strata of ashlar stones make up the structure.