The letter 'G', of course!!

It's been Athens for over 2 thousand years.

1) "Athens is the capital of Greece, but it is also the capital of the Attica Periphery and the Athens Prefecture. The city has been the capital of Greece ever since the Greek War of Independence which ended in 1832." Source: http://en.wikipedia.org/wiki/Athens 2) "During the Greek War of Independence, Nafplion was a major Ottoman stronghold and was besieged for a whole year by Theodoros Kolokotronis. After its capture, because of its strong fortifications, it became the seat of the provisional governments of Greece. Kapodistrias made it the official capital of Greece in 1829. After his assassination there in 1831 a period of anarchy followed, until the arrival of King Otto and the establishment of the new Kingdom of Greece. Nafplion remained the capital of the kingdom until 1834, when King Otto decided to move the capital to Athens." Source: http://en.wikipedia.org/wiki/Nafplion#History_of_Nafplion 3) It must be noted that Greece did not exist as a nation before the Greek War of independence. So as there was no such thing as "Greece", there was also no capital: "The basic unit of politics in Ancient Greece was the polis, sometimes translated as city-state. "Politics" literally means "the things of the polis." Each city was independent, at least in theory. Some cities might be subordinate to others (a colony traditionally deferred to its mother city), some might have had governments wholly dependent upon others (the Thirty Tyrants in Athens was imposed by Sparta following the Peloponnesian War), but the titularly supreme power in each city was located within that city. This meant that when Greece went to war (e.g., against the Persian Empire), it took the form of an alliance going to war. It also gave ample opportunity for wars within Greece between different cities." Source: http://en.wikipedia.org/wiki/History_of_Greece 4) for people interested in word games, "G" ist the capital in the word "Greece"

Athens, was there ever any question. It has been the capital since BC

Athens ofcourse!!!