Gruissan is a commune in the Aude department in southern France.

Situated on the Mediterranean coast of Southern France, Gruissan is situated in the Parc naturel régional de la Narbonnaise en Méditerranée. Traditionally a fishing village, the circular town is built around the former castle; a château of which only the Tour Barberousse remains.

The Tour Barberousse (in English, Redbeard Tower) is all that remains of a castle built at the end of the 10th century to observe the approaches to the harbour at Narbonne and to guard against seaborne invasions of the city. Built on a steep, rocky hill, the castle was enlarged in the 12th century by the Archbishops of Narbonne, Guillaume de Broa.

In the 16th century it was dismantled on the orders of Richelieu and has been left neglected since then. Although the former king had granted religious freedom to the country's inhabitants, the Roman Catholic Church resented the developing prosperity of people of other religions and Cardinal Richlieu led the movement to rid France of anyone who did not bow down to papacy, resorting to torture and death to those viewed as heretics. This was the era of Alexandre Dumas' "Three Musketeers".

Today, the village of Gruissan surrounds the castle remains. The view from the castle site over the village and surrounding coastline is quite spectacular. The tower and the ruins of the castle are listed as a monument historique by the French Ministry of Culture.