what is the average distance of a city block
City block Since the spacing of streets in grid plans varies so widely among cities, or even within cities, it is difficult to generalize about the size of a city block. However, as reference points, the standard square blocks of Portland, Houston, and Sacramento are 264 by 264 feet (80 m × 80 m), 330 by 330 feet (100 m × 100 m), and 410 by 410 feet (120 m × 120 m) respectively (to the street center line). Oblong blocks range considerably in width and length. The standard block in Manhattan is about 264 by 900 feet (80 m × 274 m); and in some U.S. cities standard blocks are as wide as 660 feet (200 m). The blocks in Calgary, Canada, are 330 by 560 feet (100 m × 170 m), while those in Edmonton, Canada are 197 by 560 feet (60 m × 171 m).[2] The blocks in central Melbourne, Australia, are 330 by 660 feet (100 m × 200 m), formed by splitting the square blocks in an original grid with a narrow street down the middle. In Chicago, Illinois and Minneapolis, Minnesota, a typical city block is 660 by 330 feet (200 m × 100 m) (w × h),[3][4] meaning that 16 east-west blocks or 8 north-south blocks measure one mile.
Great Wall of China The Great Wall stretches from Dandong in the east to Lop Lake in the west, along an arc that roughly delineates the southern edge of Inner Mongolia. A comprehensive archaeological survey, using advanced technologies, has concluded that the Ming walls measure 8,850 km (5,500 mi).[4] This is made up of 6,259 km (3,889 mi) sections of actual wall, 359 km (223 mi) of trenches and 2,232 km (1,387 mi) of natural defensive barriers such as hills and rivers.[4] Another archaeological survey found that the entire wall with all of its branches measure out to be 21,196 km (13,171 mi).[5] Today, the Great Wall is generally recognized as one of the most impressive architectural feats in history.[6]