Jackson Square (formerly Place des Armes) is a city-block sized open park, at the old center of the city. After the Battle of New Orleans it was named after victorious general Andrew Jackson; an equestrian statue of Jackson is in the center of the park.

The square originally overlooked the Mississippi River across Decatur Street, but the view was blocked in the 19th century by the building of larger levees. The riverfront was long given to shipping, but the administration of Mayor Moon Landrieu put in a scenic boardwalk along the river across from the Square; it is known as the "Moon Walk" in his honor.

On the opposite side of the square are three 18th century historic buildings which were the city’s heart in the colonial era. The center of the three is Saint Louis Cathedral. The Cathedral is designated as a minor Basilica by Pope John Paul II. To its left is the Cabildo, the old city hall, now a museum, where the finalization of the Louisiana Purchase was signed. To the Cathedral’s right is the Presbytere, built to match the Cabildo. The Presbytere originally housed the city’s Roman Catholic priests and authorities, it was then turned into a courthouse at the start of the 19th century, and in the 20th century became a museum.

On the other two sides of the square are the Pontalba Buildings, matching red-brick block long 4 story buildings built in the 1840s. The ground floors house shops and restaurants; the upper floors are apartments that are the oldest continuously rented such apartments in North America.

Directly across from Jackson Square is the Jax Brewery building, the original home of a favorite local beer. After the company ceased to operate independently, the building was converted into several businesses, including restaurants and specialty shops. In recent years, some retail space has been converted into luxury condominiums.

From the 1920s through the 1980s the square was famous as a gathering place of painters of widely varying talents, including proficient professionals, talented young art students, hacks, and dreadful caricaturists. In the 1990s the artists were largely driven away by tarot card readers, mimes, and fortune tellers.

Live music is a regular feature of the square. Occasional formal concerts are held here, but for a century or more musicians playing for tips have set up in the square, the subject of unending controversy with nearby residents.