"Freestanding" is defined by Merriam-Webster as "standing alone or on its own foundation free of support or attachment," as in a freestanding wall.
If a structure is not freestanding, then it is a supported structure. Non-freestanding structures include those such as cable-supported, air-supported, frame-supported, and tensile structures.
Some of the tallest freestanding structures in the world are the CN Tower in Canada, Oriental Pearl Tower in Shanghai, Fernsehturm Tower in Germany, World Financial Center in China, Trump International Hotel in the United States, and Burj Khalifa in the United Arab Emirates, which, as of 2010, is the tallest freestanding structure in the world.