Here are instructions on how to get a transit stamp to allow you to leave the airport in Beijing. This is NOT as visa, nor do you need one if you are staying less than 24 hrs. I saw many questions, and and since I just did it, I thought I'd post what I did. It was seemless, smooth, not a bat of an eyelash, and perfectly legal.
- international to international connection
- baggage checked through (although I don't think this matters)
- onward ticket or boarding pass
1. Take an Arrivals/Departures card from the flight attendants on the airline. You will not have a visa number, nor a place to stay, so don't fill that out, but fill out everything else (name/passport#, etc).
2. When you arrive, you will eventualy get to an open area in which there are International Transfer Desks as well as Immigration. DO NOT go to the International Transfer Desk, as that will take you to T3 and you won't be able to get out.
3. Go towards the Immigration counters. There are 3 types of lanes: Chinese Nationals on the right, Foreigners on the left, and the last lane on the left is marked "Special Lane". There is a sign there indicating that if you are in international-international transit, and if you have checked bags, then you can get a stamp to allow you to "leave the restricted area temporarily".
4. Go to the Special Lane. Many passengers who are continuing on internationally, but via a domestic airline will also be in this line. I simply presented my passport (Canadian), my copy of my onward flight/itinerary (printed at home), and my baggage tag indicating my bags were checked through. Stamped passport 30 seconds later.
5. Retain the departure card.
6. Enjoy Beijing. Do a tour - plenty of them available to take your money and take you to the sights. I hiked the Great Wall for 3 hrs.
7. When you are ready to go back to International Departure / T3, get your boarding card from your airline, and proceed to the gate like everyone else. You will present your departure card at Immigration, like everyone else, and proceed thru security.
7. Voila - you have exited and entered the airport, legally, and without any hassle.
I had someone make a call to immigration at Beijing, to confirm for me (in Chinese), that this is possible, and acceptable. If you'd like to confirm yourself, the numbers are:
8610-58105400\ 64530880\ 64563610