Piazza del Popolo is a large urban square in Rome. The name in modern Italian literally means "People's Square", but historically it derives from the poplars (populus in Latin, pioppo in Italian) after which the church of Santa Maria del Popolo, in the northeast corner of the piazza, takes its name. The piazza lies inside the northern gate in the Aurelian Walls, once the Porta Flaminia of ancient Rome, and now called the Porta del Popolo. This was the starting point of the Via Flaminia, the road to Ariminum (modern-day Rimini) and the most important route to the north. At the same time, before the age of railroads, it was the traveller's first view of Rome upon arrival. For centuries, the Piazza del Popolo was a place for public executions, the last of which took place in 1826.

The fountain was commissioned by Pope Urban VIII. It is Bernini's first work of this genre but it already shows the characteristics of his later fountains. Gian Lorenzo Bernini brought the fountain sculpture from the villa to the city, from the natural to the social setting. With him, the sculpture is conceived in relation to the water, to its ceaseless flow, to its shape and course, and thus it becomes one of the "symbolic forms" of the Baroque. The Triton Fountain is composed of four dolphins whose tails mesh together to support an enormous shell on which stands a muscular triton blowing for all he is worth into a conch. The intention behind the fountain was to create a water display that would provide an architectural reminder of the water supply provided by the Acqua Felice acqueduct commissioned by Urban VIII. What the Pope needed was a water supply for his new residence and the surrounding area. Bernini invested this practicality with a symbolic dimension.