This page contains information about a typical Venetian wellhead.
A wellhead, vera da pozzo, is the only exposed part of the well system in Venice. The wellhead served as a cap on the well to prevent debris from falling into the well and contaminating the fresh water supply. As the well system is no longer the main source of fresh water for Venetians; the Venetian Wellhead is now only considered public art and a vital aspect of the city's historical and artistic value. see Public art preservation
A wellhead, known locally as “vera da pozzo”, is the visible cap to an underground [well] that stored and filtered rain water in Venice. The term ‘vera da pozzo’ and it’s many alternatives – anello, corona, sponda, cinta, parapetto, spalletta or bocca di pozzo – has been in use since as early as the eleventh century.  As a centerpiece of many public squares in Venice, “They were always at the center of socialization and interactivity among Venetians” . The typical wellhead features inscriptions and carvings of saints or family crests. The artistic and structural design of each wellhead is indicative of the art period it was built in. 
Churches were once responsible for locking and unlocking the well at certain times of the day. This was to prevent just anyone from retrieving water from the well at any given time. In order to retrieve water from the well, Venetians typically used ropes to haul buckets of water over the lip of the wellhead. These ropes left grooves in the material of the wellhead as seen below. Some private wellheads have a pulley system installed to retrieve water without damaging the wellhead.
A typical wellhead has a platform, the main body and lid. Some platforms are made up of up to three steps. 
A typical wellhead has an overall cylindrical or square shape. Often the shape of the base and the shape of the rim are different. The shape of the base is consistently circular while the shape of the rim varies between circular, square, hexagonal and octagonal.
A Wellhead is constructed with either brick, Istria stone, Red Verona or White Verona. A brick wellhead however will deteriorate over time and as a result the typical wellhead of today is made of Istria Stone, Red Verona or White Verona with only a few exceptions. See Wellheads page. Istria stone is a type of limestone that has a gray-green or yellowish color. Lengthy exposure to the atmosphere causes the stone to obtain a whitish appearance through a process called “whitewashing.” Unfortunately, this also makes Istria stone a prime candidate for exfoliation. Verona marble is a sedimentary rock composed of organic limestone and fossils. It has either a reddish or whitish color depending on the carbon compounds it contains.
The Lid of a wellhead is typically circular in shape and either flat or convex in shape. The material of the lid is typically metal, wood or concrete with a few exceptions.
In the past, these wellheads served as access points to fresh water for not only the human population of Venice, but the animals as well. Small, bowl-shaped indentations were made in the platforms of some wellheads. These indentations served as a source of fresh drinking water and as baths for the local wild life.