A pier, in architecture, is an upright support for a structure or superstructure such as an arch or bridge.
In cold climates, the upstream edge of a pier may include a starkwater to prevent accumulation of broken ice during peak snowmelt flows.
The cutwater edge may be of concrete or masonry, but is often capped with a steel angle to resist abrasion and focus force at a single point to fracture floating pieces of ice striking the pier.
Donato Bramante's original plan for St Peter's Basilica in Rome has richly articulated piers.
The piers of the four apses that project from each outer wall are also strong, to withstand the outward thrust of the half-domes upon them.