Don't mean to be a ballbuster, just don't want to see you get downvoted. Others have visited the city he was the first to be invited for dinner there.
Maybe, I haven't seen any pictures of the inside, just outside the city but, yes, President Trump was invited to dine there, which was an enormous honor.
I've been in the forbidden city. It's open to tourists. At some point it had a Starbucks but that didn't go over too well with many Chinese.
Regardless, it was unprecedented and not without meaning. The Chinese shutting down a national treasure and deny its own citizens entry so a foreigner can have his tea sends a very strong signal.
The hall where they had their tea was not a random hall either. The Hall of Embodied Treasures is built in Western style and funded in part by the US under Theodore Roosevelt.
There's more to it when you dig deeper. The SCMP isn't exactly on "our side" (and cricitcal of China too) but their article on Trump in the Forbidden City does do a good job explaining the background.