The "gateway to northern Europe," Gothenburg is the country's chief port and second-largest city with everything a modern city can offer. The Gothenburg Botanical Garden has been named The Most Beautiful Garden in Sweden and the third most beautiful in the World. Here you can enjoy 13,000 different species of plants, stroll around in the Wood Anemone Valley gully. Next to the botanical garden is Gothenburg's largest park, Slottsskogen, where the Natural History Museum is located. The park is also home to the city's oldest observatory. One of Gothenburg's most popular tourist attractions is the archipelago (Southern Gothenburg Archipelago), which can be reached by boat. Alvsborg Fortress, Vinga and Styrso islands are popular places to visit. The amusement park Liseberg, the largest of its kind in Scandinavia, is situated in the centre of the city.