Apparently, the world’s first presidential/legislature form of government was set up in Corsica when they declared independence from Genoa, see Pasquale Paoli - Wikipedia. This says at one point:
Of course, this is not continuous. It was overthrown by Napoleon (native Corsican and one time supporter of Paoli) and has been part of France ever since.
There is a suburb on the main line of Philly named Paoli. It was named after the founding president of Corsica, Pasquale Paoli (see Wiki article on Paoli, PA) and I have long assumed that that reflected a significant influence of the Corsican constitution on the US’s.