The Gate can be visited
Tour Carbonnière

Amidst the marshes near Saint-Laurent-d'Aigouze in the French department of Gard stands the Tour Carbonnière. As a late 13th-century watchtower, it served to protect the fortified city of Aigues-Mortes.
History+
The Tour Carbonnière was first mentioned in a document from 1346. A text from this period describes it as the “key to the kingdom in this region.” The fortress was the only access to Aigues-Mortes through the surrounding marshes, and a toll was levied for its passage. A garrison consisting of a squire and several guards secured the tower, whose terrace could support up to four artillery pieces. It has been classified as a historical monument since 1889.
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: 43.5922, 4.2094