Which fortress in Haiti, built after its independence, is a World Heritage Site?

The fortress in Haiti built after independence that is a World Heritage Site is Citadelle Laferrière.

Also called the Citadelle Henri Christophe, this enormous mountain fortress stands near Milot in northern Haiti. Henri Christophe commissioned it after Haiti declared independence in 1804, intending it to protect the new nation against a possible French invasion. Construction began in 1805 and was completed around 1820, using the labor of tens of thousands of Haitians.

The fortress occupies a mountaintop roughly 900 metres above sea level. Its thick walls, huge artillery stores and food-and-water facilities were designed to support thousands of defenders for an extended siege. Although the anticipated French attack never came, the Citadelle became one of the most powerful symbols of Haitian independence and self-determination.

The site is not a standalone UNESCO property: UNESCO inscribed it in 1982 as part of the “National History Park – Citadel, Sans Souci, Ramiers.” Sans-Souci Palace, also associated with Christophe, is therefore a related World Heritage monument, but it is not the fortress described in the question.