Port Louis has conserved many historic and colonial buildings through years. One of them is a fortification named Fort Adelaide or La Citadelle, built by the British in 1835. The latter dominates the city. From there, one can observe most of the city's architecture. Port Louis is surrounded by a mountain range, called the Port Louis Moka Range. Among its most famous mountains are Le Pouce and Pieter Both which stand about 800 metres from sea level. One of the most popular spot, is the country's national derby called Champ de Mars, the latter is the oldest race course (1812) in the Indian Ocean and the second oldest in the southern Hemisphere. Other famous spots are the Police Barracks known as Les Casernes and the Port Louis Waterfront. But the feature that probably strikes the most is the city's skyline which is by far the best in the country. The skyline of Port Louis has completely changed in the last fifteen years mainly due to construction booms in the 1990s and 2000s, where many of the tallest high-rise buildings have been built. The city centre has the tallest buildings in Mauritius, including some skyscrapers. The capital has also three museums which are: the Mauritius Natural History Museum, the Blue Penny Museum and the Mauritius Stamp Museum. The biggest and oldest post office in Mauritius is found near the Caudan Waterfront. Situated in the heart of the city, the Place d'Armes is easily recognizable by its tall palm trees. It is the main entrance to and out of Port Louis.