La poudrière de Cayenne

It was built in 1865 to store the gunpowder needed for the defence of the colony.

No, the powder magazine is not open to the public for interior visits, but its architecture can be admired from the outside.

Yes, it was listed as a historic monument in 1989, having previously served as a warehouse and then a museum.

It is situated behind the Prefecture of French Guiana, in the direction of the old port of Cayenne: a path branches off to the right before the jetty.