Dense rain forest once covered the ruins and hid the site from the world until Hiram Bingham re-discovered it in 1911.
It's no wonder Machu Picchu is called the City in the Clouds, as well as the Lost City of the Incas.
From this view, the grand central plaza demonstrates its importance. With so much of the city perched on the steep hillside, a level place to congregate and walk was important.