Because Quito is about long and at its widest, most of the important avenues of the city extend from north to south. The two main motorways that go from the northern part of the city to the southern are Avenue Oriental (Corridor Periférico Oriental) on the eastern hills that border the city, and Avenue Occidental on the western side of the city on the Pichincha volcano. The street 10 de Agosto also runs north to south through most of the city, running down the middle of it. The historic centre of the city is based on a grid pattern, despite the hills, with the streets Venezuela, Chile, García Moreno, and Guayaquil being the most important.