Rules of the Grand Palace
A must-see for any visitor to Bangkok. Even if you only have one day, you must go here.
Because it is a religious site, there are a few rules regarding attire for visitors to the Grand Palace.
1. You must wear long pants or a long skirt. Nothing that shows the knee. Capri-length trousers are probably ok.
2. You must wear a shirt that covers your shoulders and arms at least to the elbow. No tanks, or short sleeves.
3. You must wear shoes that cover your feet. Specifically the toe, they must be closed-toe shoes.
These rules do seem to be bent from time to time, as I saw a couple of people in T-shirts. However, I also saw many tourists in shorts and T-shirts being turned away. If you want to be sure of getting in, you are better to err on the side of being covered.
Yes, the weather is hot and you won't want to wear a lot of clothes but keep in mind that Thai people dress conservatively, and this is a religious site for them.