Piazza Unità d'Italia (Unity of Italy Square in English) is the main square in Trieste, a seaport city in northeast Italy. Located at the foot of the hill with the castle of San Giusto, the square faces the Adriatic Sea. It is often said to be Europe's largest square located next to the sea. The square was built during the period when Trieste was the most important seaport of the Austrian-Hungarian Empire and includes the city's municipal buildings and other important palaces.
Before 1919 it was known as Piazza Grande, or Great Square. The local Slovenes still refer to it as Veliki trg (Great Square), both in daily speech and in the media. In the last decade, the term Trg zedinjenja (Unity Square) or Trg zedinjenja Italije (Unity of Italy Square) has also become popular, especially in official documents.
The square itself has occasionally been used as a concert venue, with Green Day using the square as a venue for a show on their 99 Revolutions Tour in 2013.
Coordinates: 45°39′00″N 13°46′04″E / 45.65000°N 13.76778°E