And you can stay there for under $100 per night.Grossarl Valley in National Park Hohe Tauern, Austria.Credit: unikatdesign/Getty ImagesThe U.S. may be home to some of the most beautiful national parks on Earth, but Europe has plenty of gorgeous green spaces worth exploring, too. And thanks to U.K. company Quotezone’s 2026 European National Park Index, you don’t have to guess which one to visit next. In July, the company published its findings af…