The convent contains a museum with Spanish treasures, and you can climb the belltower for spectacular views of Old Havana.
The convent does not contain a museum and offers no views of old Havana. 
mnli hypothesis: The convent does not contain a museum and offers no views of old Havana.  premise: The convent contains a museum with Spanish treasures, and you can climb the belltower for spectacular views of Old Havana.