Bagan is a must-visit place in the whole of Burma. If you visit the country, no matter how long you stay for, I guarantee that you will come here. The area still doesn't have that touristy vibe about it and you can feel like the new Christopher Columbus, discovering new lands.
Bagan, once the capital of Burma, had almost 10,000 stupas and pagodas built mainly during 11th - 13th centuries. A lot of them have been damaged by the weather, earthquakes and people themselves, but there are around 2,000 still surviving today. In the 90s the Burmese goverment decided to re-build some of the temples to make Bagan the international tourist destination.
There are a couple of main temples, which are usually visited by everyone, like Aramavati temple. These ones are busy, full of tourists and locals, trying to sell different things from books to fruits.
You can avoid the hussle by renting a bike, which costs around 1500 Kyats for a whole day. Cycling is hard, especially in the heat, but it will allow you to reach some of the unknown and unvisited temples. I felt like I was discovering a completely new world!
Another way to visit the temples is to hire a horse carriage. It is a pleasant ride, but you need to remember that the driver will take you to places where other locals can also make some money. Negotiate the route first, or take a bike one day and a carriage a bit later.
Don't forget to climb the temples, whenever possible. Most of the smaller ones have the staircases closed, but each of them have a key master, who can open the stairs for you. Of course, climbing the Sunset Pagoda (Shwesandaw) is a must.
The temples have a magical feel to them. I think the most wonderful thing about it is that the locals lead normal, undisturbed lives around them. They have feeding grounds for the cows and vegetable fields just next to the Shwesandaw Pagoda, where so many people come to admire the views from the top. All these things go together perfectly and there is no clash between them.
There is no cost of visiting the temples. You need to pay 10$ for a week when you enter the Bagan area. Keep the ticket with you as you might be asked to show it from time to time.
Other things you need to remember about:
-dress modestly; no shorts, vest tops etc, especially for women
-have a respect for the locals and don't disturb them during their prays
-before setting off, take a map and some water-you will need it, even if you take a taxi or a horse carriage