A portico (from Italian) is a porch leading to the entrance of a building, or extended as a colonnade, with a roof structure over a walkway, supported by columns or enclosed by walls. This idea was widely used in Ancient Greece and has influenced many cultures, including most Western cultures.
Some noteworthy examples of porticos are the East Portico of the United States Capitol, the portico adorning the Pantheon in Rome and the portico of University College London. Porticos are sometimes topped with pediments.
Bologna, Italy, is famous for its porticos. In total, there are over 45 km (28 mi) of arcades, some 38 in the city center. The longest portico in the world, about 3.5 km (2 mi), extends from the edge of the city to Sanctuary of the Madonna di San Luca. In Bologna, Italy, porticos stretch for 18 km (11 mi).
Palladio was a pioneer of using temple-fronts for secular buildings. In the UK, the temple-front applied to The Vyne, Hampshire was the first portico applied to an English country house.
A pronaos (UK /proʊˈneɪ.ɒs/ or US /proʊˈneɪ.əs/) is the inner area of the portico of a Greek or Roman temple, situated between the portico's colonnade or walls and the entrance to the cella, or shrine. Roman temples commonly had an open pronaos, usually with only columns and no walls, and the pronaos could be as long as the cella. The word pronaos (πρόναος) is Greek for "before a temple". In Latin, a pronaos is also referred to as an anticum or prodomus.