Niche Market in La Antigua Guatemala
No, I don’t think you were thinking about this niche market. Although these kind of niches are the origin for the concept of niche market. Well, the play on words may not work completely in English as it does in Spanish. Nicho is the Spanish term for niche and it applies to the market place, to an architectural recess, to a hollow, crack, crevice, or foothold, and from there to the hollow structure pictured above to receive the dead.
What do you call these hollow boxes in your part of town?

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August 7th, 2007
Here they are called “above ground crypts or mausoleums” such as the one Marilyn Monrow is buried in.
http://www.steelcactus.com/lanico01.jpg
Sometimes you will see smaller versions of the picture above with urns containing the ashes of the deceased placed in the niches.
April 26th, 2008
In france, these little boxes for deads are “columbarium” as the holes for doves (colombes in french).