Tour CB21, formerly Tour Gan, is an office skyscraper located in La Défense, the high-rise business district situated west of Paris, France.

It was designed by celebrated American architect Max Abramovitz.

However, it reaches 187 m (614 ft) once including the antenna located on the roof.

In 1972, during construction, a protest campaign opposed the building of Tour Gan.

Today, the main tenants are Suez Environnement and AIG France.