La Garde hill rises 505 ft (154 m) above sea level and offers a 360° view of the city of Marseille, the islands, and the sea. As such, it has always been an appreciated observation post registered from the 15th century in the list of the coastal relays. It was equipped with a watchtower system that improved over the centuries and lasted until 1978. In 1524, a fort was built there to protect Marseille from the armies of Charles V. It formed a first maritime defense with the Château d'If and served as a base for the current Notre-Dame-de-la-Garde basilica.