One of the main things that makes humans special is the capacity to build. The ancient britons built stonehenge, the Egyptians built pyramids and the romans built roads. As time went on the buildings people built were bigger and more complex. Since the buildings were more complicated more precise calculations like the incline of the ground and stability of the earth were taken into account. However the curvature of the earth was not a factor in any building humans have built. Take for example the Suez canal. The Suez canal is a 100 mile canal built between the Mediterranean sea and the Red sea. When constructed the curvature of the Earth was not taken into account. You would think that over 100 miles the canal might drop 1 or 2 feet but it doesn't, its built without a slope 26 feet under sea level. Other examples of building projects that did not take into account the curvature of the earth into account include but is not limited to the Erie Canal, and the Golden Gate bridge.