Who had the first indoor plumbing?

Answer 1

The first "indoor" Plumbing credit goes to the Romans, how ever primitive it may have been. They first invented the aqueducts that carried water from the mountains and hills surrounding Rome, and were famous for the "Roman Baths".

Answer 2

Poet Henry Wadsworth Longfellow was the very first American to have indoor plumbing! :)

Answer 3

The ancient Greeks did.