Pericles had such a profound influence on Athenian society that Thucydides, a contemporary historian, acclaimed him as "the first citizen of Athens". Pericles turned the Delian League into an Athenian Empire and led his countrymen during the first two years of the Peloponnesian War. The period during which he led Athens, roughly from 461 to 429 BC, is sometimes known as the "Age of Pericles", though the period thus denoted can include times as early as the Persian Wars, or as late as the next century. Pericles promoted the arts and literature; it is principally through his efforts that Athens holds the reputation of being the educational and cultural center of the ancient Greek world. He started an ambitious project that generated most of the surviving structures on the Acropolis (including the Parthenon). This project beautified and protected the city, exhibited its glory, and gave work to the people.Pericles also fostered Athenian democracy to such an extent that critics call him a populist.