A portico 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.
The portico of the Croome Court in Croome D'Abitot (England)
Temple of Portunus in Rome, with its tetrastyle portico of four Ionic columns
The hexastyle Temple of Concord at Agrigentum (c. 430 BCE)
The western side of the octastyle Parthenon in Athens
In classical architecture, a colonnade is a long sequence of columns joined by their entablature, often free-standing, or part of a building. Paired or multiple pairs of columns are normally employed in a colonnade which can be straight or curved. The space enclosed may be covered or open. In St. Peter's Square in Rome, Bernini's great colonnade encloses a vast open elliptical space.
Colonnade at the Belvedere on the Pfingstberg palace in Germany
The colonnade of Amenhotep III at the Luxor temple
The Stoa of Attalos in the reconstructed Ancient Agora of Athens
The Great Colonnade at Palmyra, Syria