Sentence:  The <WSD>columbarium</WSD> (vaults lined with recesses for cinerary urns) in the form of a grotto (a cave-like structure) is the centerpiece of the Elks plot. 
Meaning of the word marked with <WSD> tags:  A building, a vault or a similar place for the respectful and usually public storage of cinerary urns containing cremated remains.