Waldspirale (the Wooded Spiral)
Built by the famed Austrian architect and painter Friedensreich Hundertwasser, who was known for the onion-shaped domes and curved lines seen here, this apartment complex was completed in 2000. At its highest point, the winding structure is 12 stories tall. The roof houses a cafe, a bar—and a manmade forest-garden for residents to enjoy. In total, the building contains 105 apartments and more than 1,000 windows. Some windows feature “tree tenants”—or trees planted indoors that are trained to grow out of the windows—a design element typical of Hundertwasser’s style.