Greece is a country in Europe. The capital of Greece is Athens.
Many ancestors of the New Olympian Clan originally came from Greece before finding refuge in New Olympus. Those that elected to stay behind hoped to still find a way to co-exist with the humans. 
According to a tale told by Shari, Gathelus and Scota arrived on the small island of Samothrace soon after fleeing Egypt. There, Scota gave birth to twin sons. ("The Rock")
Petros Xanatos was born in Greece.  He eventually immigrated to the United States and became a naturalized citizen.  Later in 1955, he had a son in Bar Harbor, Maine. ("Vows") 
- Greece at Wikipedia, the Free Encyclopedia