The Tour Royale (also known as La Grosse Tour) is a fort built in the 16th century to protect the entrance of the Petit Rade, the naval port of Toulon. It was the first fortification of the harbor, built 22 years after Provence became a part of France.
The fort was commissioned in 1513 by King Louis XII at the request of the bishop of Toulon and of the Senechal of Provence. It was placed on the cap de la Manegue, at the end of the pointe de la Mitre, where it could fire at any ships coming into the Rade. The design was by the Italian engineer Gian-Antonio della Porta. It was a classical example of a Torrioni, a round tower with cannon, constructed around Renaissance Italy in the 16th century. The tower was sixty meters in diameter and seven meters thick. Construction began in 1514 and was finished in 1524, during the reign of Francis I of France, at a cost of 30,000 florins. Because of its impressive size, the residents of Toulon called "La Grosse Tour."
The tower had hardly been finished when it was captured by the army of Charles V, Holy Roman Emperor, led by the Connetable de Bourbon, when he invaded Provence. The Connetable avoided a long and costly siege by simply paying the commander of the fort 500 ecues to surrender. After the commander and garrison took their money and left, the fort was occupied by 300 Spanish mercenaries. This event led to the coining of an expression in Toulon, "to be sold like the Grosse Tour."
When the Imperial army left, the fort was used to imprison the chevalier Bertrande de la Garde, who had fought for Charles V against Francis I. He was the first of many political prisoners to be held in the underground cells of the fort.
In 1543, Francis I formed a temporary Franco-Ottoman alliance with the Ottoman Sultan Suleiman the Magnificent, and invited the Ottoman fleet to spend the winter in Toulon harbour. The Tour Royale was used to store all the artillery from the ramparts of Toulon, until the Ottoman fleet departed.
In 1572, when the news of the massacre of Protestants in Paris on St. Bartholomew's Day became known, the commander of the fort, Nicolas de Pignan, gave sanctuary to the Protestant families of Toulon within the fort.
In 1596, during the wars of religion across France, the commander of the Chateau D'If, who had remained loyal to Henry IV of France, had a meeting in the Tour Royale with the Duke de Guise, Governor of Provence, to agree on a way to drive the Spaniards from Marseille, which had declared itself an independent republic.'