Out of curiosity, can I, as a US citizen, enter a US embassy without a serious reason? For example, if I was traveling to Tokyo and I want to see what it looks like inside can I just walk in? If not, would it be assumed that it is by per embassy basis and I would need to contact them with my intentions for why I would like to visit? An example would be a tour and if one is given by the embassy.
I don't plan to go to an embassy to hang out or do something inappropriate. I'm genuinely curious about the interiors of the embassy.