The Fortress can be visited
Château Royal de Collioure

In the town of Collioure, a few kilometers north of the Spanish border in the French department of Pyrénées-Orientales, stands the Château Royal de Collioure. This multifaceted fortress, which evolved from at least four different castles, stands directly by the sea.
History+
The origins of the fortified site in Collioure date back to 673, when the Visigothic king Wamba besieged the “Castellum Caucolibéri” to quell a rebellion. In the 12th century, Girard II, the last independent Count of Roussillon, bequeathed his lands to Alfons II, the King of Aragon. The Kings of Aragon promoted Collioure through privileges and tax exemptions, leading to construction work on the castle, port, and town. Around 1207, the Knights Templar built their own castle, which was integrated into the royal complex in 1345. In the 13th and 14th centuries, the Kings of Majorca built a second castle, as Collioure was part of their kingdom, which also included Montpellier and the Balearic Islands. In the 16th century, after a brief French occupation, the Spanish Habsburgs, particularly Charles V and his son Philip II, modernized the castle into a fortress to adapt it to advances in artillery.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Hervé Rebours
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 42.5256, 3.0851