This one's easy: the Changing of the Guard. One of the most popular sights in Athens, the ceremony is an impressive display of precision, discipline, and stoicism. Two members of the Evzones, the elite unit of the Presidential Guard, stand watch in front of the monument and perform a ceremonial change every hour. The most dramatic change occurs on Sunday mornings at 11 am, when the entire Presidential Guard marches to the Monument of the Unknown Soldier, accompanied by a military band.