Catacombs, in Miami?

Archaeologists excavating two American Indian burial sites in downtown Miami say they have found hundreds of remains piled in limestone fissures, some of the bones layered in limestone boxes.

"In terms of the rest of Florida, we've never seen anything that's been the same," said state archaeologist Ryan Wheeler. "It's a very unusual mode of burial". . .

The remains, about five centuries old, are likely those of ancestors of the Tequesta tribe that met Spanish explorer Juan Ponce de Leon in 1513, Wheeler said.

The tribe probably kept the bones above ground for some time before mass-burying them - scooping out soil in the fissures or deep natural grooves, burying the bones and then covering the grave, Wheeler said.