The city has a history more than 1400 years which can be traced back to the 7th century when the King Srongtsen Gampo moved the capital to here. Lhasa, literally the place of the Gods, is the hub of Tibet for transportation, education, religion etc. with a population of 550,000 (2013) and 83% are Tibetans. The altitude of Lhsa is about 3600 meters, it is highly suggested to acclimatise for your first day to do nothing.
You can choose flight or trains from various cities in China to Lhasa, such as Chengdu, Chongqing, Xining, Lanzhou, Beijing, Xian and Shanghai.
It is a once-in-the-life experience to take the train from Xining to Lhasa, on the way you can endless snow-covered mountains, green lakes, Tanggula Range(5200 meters), yaks, etc. The climate in Lhasa is quite warm during the daytime as the sun shine is very strong, but quite chilly in the night even in Summer.
In winter, it is still very nice to visit Lhasa, you can wander in the daytime around Potala Palace and Jakhang Monastery, Barkhor Street.