Karl Vorwerk wrote:

I like broken glass cemented on the top of concrete or brick wall or the
wrought iron fences in Charleston, SC with the roller spikes on top.
Karl

I grew up in Wilmington, DE, where the duPonts were kings (literally). Alfred I
duPont had a stone wall built around his estate, topped with broken glass (it
was still there last time I visited, although it's now a prestigious children's
osteo research hospital). He claimed it was "to keep out unwelcome visitors,
especially those with the name duPont".

Joe