Carl just sent me a photo of this beautiful marble floor from Vegas (not sure which hotel it's in). It's a
Guilloche Pattern. A
Guilloche is a pattern of interwoven strands, resembling rope, often used as a border in Roman mosaics. Typically two, three or five strands would be use in the Guilloche.
Here's Carl's photo:
Here's a decorative listello we sell named the LaRose in the classic Guilloche pattern:
The Greeks used this pattern on temples and vases:
Here is a cool mosaic sink with this pattern: