The town's name is composed from the union of the words "porto" (referring to the ancient river port) and "gruaro" (from "grava", a word of Celt origins which means "gravel").
Municipality in the province of Venice, located at the eastern end of the Veneto plain, on the border with Friuli Venezia Giulia, the region is extraordinarily rich in rivers due to the presence of several springs. The town developed in two districts, connected by bridge, divided by the river Lèmene, that feature a series of artificial channels, into which reflect the noble residences of the centre in the Renaissance style. The houses bordering the river have small docks for boats and the commercial centre features arcades, built to protect the merchandise.
The original settlement was built in 1140, when the Bishop of Concordia Sagittaria, lord of the area, allowed a group of merchants to settle south of the lagoon and build a thriving trading centre, aided by the presence of Lèmene, a year round navigable river. At the time the settlement developed and extended to the other side of river. In the XIV century, thanks to a remarkable economic development, the center was granted, by the nearby Venice, with several different autonomies. From the conquest of Napoleon onwards, the town shared with the entire province, the same history.

Attractions:
- the Cathedral of St. Andrew, built in the second half of the XII century, in neo-Classical style, has been subject to several renovations in the second half of the XVIII century. It is flanked by an imposing and leaning Bell Tower in Romanesque style;
- the XIII century Church of Saints Christoforo and Luigi;
- the XIV century Church of San Giovanni;
- the Oratory of the Madonna of Peschiera;
- the XIII century Church of Saint Agnese;
- the XI century Abbey of Summaga;
- the Chapel of the Visitation;
- the Church of Saint Luigi;
- the XIV century Town Hall, in Gothic style, features a brick façade with Guelph battlements on the gable roof, Gothic windows and an external staircase;
- the XV century Mills, located along the course of the river;
- the Port of Borgo San Gottardo;
- Palazzo Venanzio;
- Palazzo Marzotto;
- Palazzo Fasolo;
- Palazzo Pari;
- the Museum of Paleontology;
- the National Museum.