Most Thai people are Buddhists so you can see many temples or Wats all over Thailand from North to South or from East to West. For Thai people, Buddhist temples provide relaxing places for someone who would like to have a break from some anxiety. They are very quiet places and you will have a peace of mind while staying there. (you will experience a sensation of tranquility and peace) For you, as a foreign tourist, you will also find those temples very wonderful esp. in Bangkok, the capital city of Thailand. There are a lot of temples that would be highly recommended for you to visit as you will see here below top lists of temples that you won't miss:
) Wat Phra Kaew or The Emerald Buddha
This is the most important Buddhist temple in Thailand. The Emerald Buddha which was carved from jade is situated here. The King changes the robes covering the Emerald Buddha three times a year; summer, winter and rainy season. The temple is very beautiful and you can take tons of photos there.
) Wat Arun or Temple of the Dawn
This temple has a very beautiful architectual style and very tall Chedi. You can climb up the stairs to the top which are a real challenge because the stairs are very steep small and vertical.
) Wat Pho or Wat Phra Chetuphon or the Temple of he Reclining Buddha
This is the oldest and largest temple in Bangkok. It is also known as the first university of Thailand. There are a lot of Buddha images (more than Buddha images) The largest Buddha images of Thailand the Reclining Buddha (Phra Buddhasaiyas) is also situated in this temple. ( meters long and meters high)
) Wat Benchamabophit or the Marble Temple
This temple was built entirely by white marbles (imported from Italy) which is very wonderful. Phra Buddha Chinnarat is one of the most beautiful Buddha images in Thailand. There are many Buddha images lining in the courtyard. You are invited to visit this temple in the morning when the Buddhist monks are chanting inside the chapel.
By the way, when you plan to visit Thai temples which are, as you know, considered to be a sacred places in Thailand, you have to dress appropriately and respectfully. Women must wear skirts or dresses and no sleeveless or revealing blouses. Men don't go shirtless or don't wear shorts or a bathing suit. No slippers, sandals, or revealing tops. When taking photos, please do not sit or lean on the status of Buddha.
In short, in my opinion, top lists of temples in Bangkok as mentioned above are the ones that you must not miss from your traveling schedule. Have a wonderful traveling to Thailand!