Hola Emanuel
Using "en" would be very similar to using "por", but, as we say in our note inside the lesson:
"The way the preposition por is used in this context is very similar to the way we use preposition en to say "in/on"a place, although when using por there is a stronger nuance of meaning "approximate place" or "around somewhere".
So, it wouldn't mean exactly the same.
Hope it helps
Inma :))
