nauplion is a greek city. it is in the argolida's prefecture, in the east of peloponnese peninsula. near nauplio is the historical city of argos. nauplio was the first capital of greece. nauplio is a coastal city. it has three castles. the most famous are the palamidi castle, and bourtzi castle which is on the islet in front of the port. the population of nauplion is 13,124 inhabitants.