Towers and bridges are urban, engineered structures that lay the groundwork for the development of cities. Construction of tall, grand towers has been swiftly under way in Tehran's metropolitan area for more than a decade, and the special terms of residential and commercial are no longer applicable in architecture. Meanwhile, bridges also serve as non-planar intersections and have become important urban elements. Bypasses are mostly for vehicles and serve as a means to control traffic, but others provide a safe crossing for pedestrians. Among attractions in Tehran are two tall, famous towers, also landmarks of the city, Azadi and Milad Towers. Pol Tabiat (Nature Bridge) is a special location providing a link between Taleghani and Ab-o-Atash (Water and Fire) Parks. From Pol Tabiat, you can see Tehran in all its glory.