Lan was a wonderful guide.  He showed my husband and I the major sights in Phnom Penh including the royal palace, the genocide museum and Wat Phnom.  He knew the history and details of each site and his English was impeccable.  He was also very considerate (offering cold water) and ensuring easy assess to each site.  In addition, his driving was very safe!  We would highly recommend him to anyone interested in being shown around Phnom Penh.