Perched high above the sprawling city, the Acropolis is the heart of ancient Athens and an unforgettable sight. You'll want to wear comfortable, sturdy shoes for the walk up the rocky path, which takes about 20 minutes, as the marble can be quite slippery. Once at the summit, you're rewarded with breathtaking views and the chance to walk among iconic structures like the Parthenon. It gets very sunny with little shade, so an early morning or late afternoon visit is best to avoid the midday heat and the biggest crowds.