It wasn't until this site did I know there are people with aphantasia but also have the ability to dream with at least some imagery details. To answer your que

It wasn't until this site did I know there are people with aphantasia but also have the ability to dream with at least some imagery details. To answer your question. Nothing. It is just black. Not even a slight hint of shape of Eiffel Tower or even a tall rectangle or just outline of the structure. It is just nothing. I sometimes think or wonder people who can dream and close their eyes and actually see things must have so much fun.