My Treasure Chest

This was my parents which I've recently acquired. They went antiquing with their wedding gift money and found many very cool things.
The brass plaque on front reads:
REAL ADVANA E/D
PUERTO RICO 30 DE
NOVEMBRE DE 1826
ANTONIO GRANELA
I've tried to locate more info but haven't been able to find anything.
There is one small shelf along the inside right. It weighs about a ton. In pretty good shape I think, though the iron is starting to show some rust. I'd like to keep it but I think it could use some TLC. The picture doesn't do it justice.