Under no circumstances should a city pour a slab of concrete to build temporary ramps as the funds would be much better spent building a permanent concrete skatepark to begin with. Most concrete skateparks will cost between 20 and 25 dollars (USD) per square foot to build.
From the ground to the roof it is 442 meters (1,450 feet) tall. It was designed by Fazlur Khan and Bruce Graham. Willis Tower is the second-tallest building in the United States. It is the eighth-tallest freestanding structure in the world. It is one of the most popular tourist destinations in Chicago.
Circle of Willis: A critical arterial circle at the base of the brain. The circle of Willis receives all the blood that is pumped up the two internal carotid arteries that come up the front of the neck. All the principal arteries that supply the two halves of the brain (hemispheres) branch off from the circle of Willis.