When I lived in Mainz, Germany my class went to the Gutenberg Museum. I found it pretty cool, seeing the ancient books and printing presses.
I wouldn't call it a school trip, more like a teacher accompanied trip, we went to a small seaside city for a few days, it was wild
It was last year in Vienna in the Christmas markets.
The Bodies Exhibit in Atlanta
I think it' be visiting the state capitol in 9th grade.
In elementary level - 4th grade, maybe? It was a field trip that would, one day, help us to discover nature's mysteries. She pointed out various features and their names like: trunk, stem, dirt... and that might be a rock.