Slovenia is one of the most forested nations in all of Europe, which means that you're never far from wooded nature – even if you're in the centre of the country's third largest city. As part of the Forest for Cities project, the municipality of Celje, in cooperation with the Slovenian Forest Service, has opened a recreational and education treehouse in the forest to the west of town on the south bank of the Savinja river. In addition to the large tree house made entirely of Douglas fir, there is a children's playground, educational trails, exercise stations and dozens of benches. Entry to the treehouse is free of charge, and it can also be rented for group events, with a capacity of up to 30 people. To get there follow the marked path from Mestni Park.