Patras is Greece's third-largest city and the regional capital of Western Greece, in the northern Peloponnese, 215 km west of Athens. The city is built at the foothills of Mount Panachaikon, overlooking the Gulf of Patras.
Dubbed as Greece's Gate to the West, Patras is a commercial hub, while its busy port is a nodal point for trade and communication with Italy and the rest of Western Europe. The city has two public universities and one Technological Institute, hosting a large student population and rendering Patras a major scientific centre with a field of excellence in technological education. The Rio-Antirio bridge connects Patras' easternmost suburb of Rio to the town of Antirrio, connecting the Peloponnese peninsula with mainland Greece.
Every year, in February, the city hosts one of Europe's largest and most colourful carnivals: notable features of the Patras Carnival include its mammoth satirical floats and extravagant balls and parades, enjoyed by hundreds of thousands of visitors in a pleasant Mediterranean climate. Patras is also famous for supporting an indigenous cultural scene active mainly in the performing arts and modern urban literature. It was European Capital of Culture in 2006.
A central feature of the urban geography of Patras is its division into upper and lower sections. This is the result of an interplay between natural geography and human settlement patterns; the lower section of the city (Kato Poli), which includes the 19th-century urban core and the port, is adjacent to the sea and stretches between the estuaries of the rivers of Glafkos and Haradros. It is built on what was originally a bed of river soils and dried-up swamps. The older upper section (Ano Poli) covers the area of the pre-modern settlement, around the Fortress, on what is the last elevation of Mount Panachaikon before the Gulf of Patras.
The largest river in the area is the Glafkos, flowing to the south of Patras. Glafkos springs in Mount Panachaikon and its water is, since 1925, collected in a small mountainous reservoir-dam near the village of Souli and subsequently pumped in order to provide energy for the country's first hydroelectric plant. The water is also used for the orchards of Eglykas and as drinking water for the city. Other rivers are Haradros, Meilichos and the mountain torrent Diakoniaris.
Of great importance for the biological diversity of the area and the preservation of its climate is the swamp of Agyia, a small and coastal aquatic ecosystem of only 30 ha, north of the city centre. The main features of this wetland are its apparent survival difficulty, being at the heart of a densely populated urban centre that features a relatively arid climate and its admittedly high level of biodiversity, with over 90 species of birds being observed until the early 1990s, according to a study by the Patras Bureau of the Hellenic Ornithological Society.
Another geophysical characteristic of the region is its high level of seismicity. Small tremors are recorded along the coast of Patras almost constantly. Larger earthquakes hit the area every few years with potentially destructive effects. In 1993, a 5.0-magnitude earthquake caused some damage to several (mostly older) buildings throughout Patras due to the proximity of the epicenter to the city. On June 15, 1995, a 6.2-magnitude earthquake hit the nearby town of Aigion, also causing some structural damage to a few buildings in Patras. The Ionian Islands are also frequently hit by even more severe earthquakes, some of which can be felt in the city. In antiquity, the most notable example of destruction caused by an earthquake in the region was the total submergence of the ancient Achaean city of Helike, now Eliki.