repurposing an aquarium

We're looking for creative suggestions for things to do with a 55
gallon aquarium. When we built the house, we built a special partition
in the wall between two rooms so the aquarium could be seen from two
rooms. We're no longer maintaining the tank (long story - big house
- empty nest) and are trying to figure out what else we can do with it.
It would have to be someting w/o maintenance (i.e., nothing alive) so
a terrarium is probably out. Maybe something 'artsy'

Any suggestions?

It needs to be something decorative from both sides, have you considered
a nice silk plant arrangment? Do you have children? When I was a child
one of my aunts made an aquarium jungle, it was a tank outfitted with
fake plants and those small toy animals.