Situated to the west of Naples, Pozzuoli is a city soaked in history. Greek colonists founded it in the 7th Century BCE, but it was under the Roman domination that it grew to be the most important port in the Western Mediterranean. The city's history is linked to a phenomenon that causes the Earth's crust to rise and fall with respect to the level of the sea. A sign of this phenomenon can be seen in the Temple of Serapis, the ancient Roman market which is periodically submerged under the waters. Other evidence of the city's rich and important past can be seen in the Anfiteatro Flavio in the higher part of the city, the Neptune thermal complex, the numerous churches, Villa Avellino and the famous Solfatara volcano.