The first fortification appeared here in 1638, when Jacques Dyel du Parquet, nephew of the colony's founder Pierre Belain d'Esnambuc and the first governor of Martinique, ordered a stronghold built to guard the settlement against attack. That original structure did not survive long. The fort was rebuilt in 1669 under the governor-general Jean-Charles de Baas-Castelmore, Marquis of Baas, and his successors redesigned it along the principles of Vauban -- the great French military architect whose star-shaped fortifications defined European defensive engineering. Charles de La Roche-Courbon, comte de Blenac, spent a decade building a 487-meter wall around the peninsula, four meters high and two meters thick. The result was a fortress strong enough to repel de Ruyter's three-day assault in 1674 and to remain the anchor of French military power in the Caribbean for generations.

Fort Saint Louis has been called Fort Royal, Fort de la Republique, and Fort Edward, depending on who held it and which revolution was underway. The British captured it repeatedly. In 1762, they took the overlooking hills of Morne Garnier and Morne Tartenson and bombarded the fort into submission from above -- exploiting its one great weakness, its vulnerability to attack from the landward side. In 1794, Admiral John Jervis invaded Martinique, and when the 64-gun ship HMS Asia could not get close enough to engage the fort, Commander Faulknor of the sloop HMS Zebra volunteered to do it alone. He ran his small vessel under the walls through heavy fire, landed his crew by boat, and stormed the fort. The British held it from 1794 to 1802, lost it when the Treaty of Amiens returned Martinique to France, and took it again in 1809 -- this time when Commander Charles John Napier of the brig-sloop Recruit noticed the fort appeared abandoned, rowed over with four men, scaled the walls, and hoisted the British flag.

That 1809 capture ended badly for the French commander. Admiral Louis Thomas Villaret de Joyeuse, who had been governor-general since 1802, was stripped of his rank and honors by a Paris court of inquiry that December, held responsible for the island's loss. The British stayed until 1814, returned briefly in 1815 after Napoleon escaped from Elba, and then left for good. The French set about ensuring they would not be humiliated again. Between 1850 and 1896, they installed artillery batteries at the fort and at Pointe des Negres to command the full sweep of Fort-de-France Bay. They also built Fort Bourbon on Morne Garnier -- the same hill the British had used against them -- to protect Fort Saint Louis from the landward approach that had proven its undoing twice.

Today Fort Saint Louis is both museum and military installation. The French Navy's Caribbean command, COMAR Antilles, operates from within its walls, home to surveillance frigates, patrol vessels, and support ships. Parts of the fort are open to daily tours; the active naval base is not. The peninsula's most unexpected residents are its green iguanas. The species Iguana iguana is not native to Martinique -- the reptiles are believed to have arrived by boat from French Guiana or the Iles des Saintes and established a colony in the fort's rocky terrain after their release or escape. Generations of iguanas have now occupied the ramparts, basking on Vauban-era stonework and watching Navy personnel come and go. The fort stands on its rocky spur at the edge of the capital, four centuries of names and flags layered into its walls -- Dutch cannonballs, British surrender terms, French military engineering, and a colony of immigrant lizards who found a fortress and made it home.