Piazza San Marco is the most prominent square in Venice and a major tourist attraction, frequented by numerous photographers and visitors. The extension that stretches from the square to St. Mark's Basin is known as Piazzetta San Marco, although it is not strictly part of the square.

Napoleon Bonaparte, although some attribute the phrase to Alfred de Musset, is said to have described it as the most elegant salon in Europe.

The history of the square dates back to the 9th century, when it was a small area in front of the ancient basilica of St. Mark, originally dedicated to St. Theodore, the first patron saint of Venice. It was later enlarged to its present shape and size in 1177, to facilitate the meeting between Pope Alexander III and Emperor Frederick Barbarossa.

Throughout history, the square has been the center of Venice, hosting important events of the Republic of Venice and being the seat of the archbishopric since the 19th century. It was first paved in the late 13th century and then renovated several times, with more complex geometric designs.

The buildings surrounding the square include the Basilica, the Ducal Palace and the Basilica's Bell Tower. In addition, there are other notable buildings such as the St. Mark's Clock Tower, the Old and New Procuracies, the Napoleonic Wing, the Correr Museum and the Archaeology Museum, among others.

Due to its low-lying location, the square is prone to flooding when water from the Adriatic Sea or excessive rainfall causes high tides. The drainage system, designed to evacuate rainwater, can have the opposite effect during high tides, allowing water from the canal to rise into the square.