The Palais Longchamp is a monument in Marseille, France that houses the Musée des Beaux-arts (“the museum of arts”) and d’Historie Naturelle , a natural history museum. Around is is the Parc Longchamp, a gorgeous park. The palace was built to celebrate the construction of the Canal of Marseille and its construction took over thirty years. The palace is divided into three parts: the chateu d’eau, the east wing, where the Musée des Beaux-Arts is housed and the west wing, where the Museum d’Historie Naturelle is located. There is also an observatory which is the oldest science establishment in Marseille and is now an instrument development laboratory and a data processing center for the largest telescopes in the world.
The palace in itself is so grand and beautiful, that despite all the other reasons Marseille is worth a visit, I would say this is one of the main ones.