Sanatorium Martel de Janville, Monument historique in Passy, France.

Sanatorium Martel de Janville is a hospital building in Passy featuring three wings arranged around semicircular entrances with a distinctive conical chimney as a visual landmark. The structure integrates various spaces for medical treatment and patient accommodation within a unified architectural design.

Construction took place in 1937 by architects Pol Abraham and Henry Jacques Le Même, creating a facility for army officers in need of medical care. Over the decades the building changed its purpose and now houses residential apartments while preserving its architectural character from that era.

The building's name honours the Countess de Martel, whose donation prompted the Ministry of War to commission it in 1932. It served officers and non-commissioned officers of the French army suffering from pulmonary tuberculosis, and the individual cure rooms were furnished by Jean Prouvé and Jules Leleu.

The site sits at an elevated location providing views across the valley, though reaching it requires traveling up mountain roads. Plan for adequate time and bring suitable footwear to explore the grounds and surrounding landscape comfortably.

On 4 December 1943 a German Focke-Achgelis Fa 223 Drachen helicopter, number 12 and registered DM+SP, crashed near the sanatorium around 13:45, killing Oberleutnant Brennecke and his assistant after a rotor pitch control link failed. Why the aircraft was in the area is still debated: one account says it was heading to rescue young alpinists of the Chantiers de la jeunesse caught in an avalanche toward Mont Blanc, another that it was carrying a V2 propulsion unit to the Mont-Lachat wind tunnel.