Two point perspective and single point perspective

http://www.youtube.com/watch?v=2baldeY881k
Two point perspective video
Drawing a room with two point perspective
http://www.youtube.com/watch?v=UP9x1322dK8

Complicated cityscape perpsective
http://www.youtube.com/watch?v=eAKOjcO_eYo


Example of single point perspective

Example of single point perspective

Example of two point perspective