An observation tower is a structure whose primary purpose is to give users a high view of the surrounding area. The purpose may be recreational or functional; for example, observation towers include fire lookout towers as well as towers that charge admission to the public for viewing.

Other types of structures (such as skyscrapers, monuments, or television towers) may also include observation platforms. A tower's usage as an observation point does not determine its building type unless its capacity as a lookout tower is the primary motive behind its design.

The elevated view can serve a practical lookout or a recreational visitor. An observation platform added to a tower designed mainly for another function does not by itself establish this structural type.