Grand Nancy Thermal, Thermal bath complex in Haussonville district, Nancy, France

Grand Nancy Thermal is a thermal bath complex in the Haussonville-Blandan-Donop district of Nancy, with a thermal centre, an aqualudic and sports centre, a wellness area and a hotel residence. The listed 1913 building includes a 50 × 18 m indoor pool, a round pool from 1914 and a source pavilion. Outside, a 50 m sports pool was added in the 2020s.

Architect Louis Lanternier drilled for a thermal spring in 1908; the source bears his name and was inaugurated at the 1909 Exposition internationale de l'Est de la France. In 1913 the baths and a 50 × 18 m pool opened, then the largest thermal-water pool in the world. The water rises at 36 °C and yields 1,500 l/min. The main hall, round pool, source pavilion and galleries were listed as monuments historiques on 3 November 2020.

Grand Nancy Thermal is one of the few thermal facilities in France still operating inside a building from the early 20th century. The round pool in the main hall gives the place a character that feels very different from modern wellness centers.

The complex sits in south-west Nancy, bounded by Parc Sainte-Marie to the east, rue du Sergent-Blandan and the Meurthe-et-Moselle departmental council building to the west, the Frédéric-Chopin school campus to the north and avenue du Maréchal-Juin to the south. The outdoor 50 m pool, the four-lane pentagliss slide, the two-level diving board with its dedicated pit and the climbing wall over the diving pool operate in the warm season only; the indoor slide is open all year. The site is listed as a monument historique.

The thermal water rises naturally from underground at a steady warm temperature without any need for heating. This natural flow was the reason a bathing facility was built on this exact spot in 1908 and not somewhere else in Nancy.