Square de la tour Saint-Jacques, Urban park in 4th arrondissement of Paris, France.

The Square de la Tour Saint-Jacques is a rectangular green space of 6,016 m² in the Saint-Merri quarter, bordered by Rue de Rivoli, Avenue Victoria, Boulevard de Sébastopol and Rue Saint-Martin. At its centre stands the 16th-century Gothic Tour Saint-Jacques, remodelled by Théodore Ballu. A flat lawn is framed by a gravel path with blue slatted benches, and a flower bed edged with low metal hoops sits to one side.

The tower originally belonged to a medieval church that once occupied this location before it was demolished. In the 19th century, the city transformed the grounds into a public garden, turning the site into an open space for the neighborhood.

The square is named after the church of Saint-Jacques-la-Boucherie, demolished in 1797, whose 16th-century Flamboyant Gothic bell tower survived. Since 7 June 1990 one of its paths has been called allée Waslaw-Nijinsky, after the Ballets Russes dancer who performed at the nearby théâtre du Châtelet in the 1910s and 1920s.

The park sits in a busy neighborhood and is easy to reach on foot from surrounding streets. You can visit anytime during daylight hours, and it makes a convenient stop if you are exploring the area around Châtelet.

A memorial to scientist Blaise Pascal marks the spot where he conducted experiments on air pressure in the 17th century. This connection ties the space to a pivotal moment in scientific inquiry.