Beijing is an international arrival hub for foreign travelers. Besides, there are multiple flights and daily train you can take to go to Tibet from Beijing.You are suggested to stay 3 or 4 days to see the highlights before heading to Tibet. You can spend a day to visit the central city area where you can see Forbidden City, Temple of Heaven. In another day, you can go to hike the Great Wall.After 3~4 days stay in Beijing, tourists can go to Lhasa by train or by plane. It takes 44 hours to arrive at Lhasa by the only daily train from Beijing. It’s a long-time traveling but you can have the wonderful sightseeing along the Qingzang Railway; the other hand it can help you acclimatize to the high altitude step by step.