By car:
From the E62 (A1) "Autoroute de contournement" ring road.
Follow signs for Genève Perly to the A1a motorway segment.
Exit A1a after about 2 km following signs for Carouge.
Follow Chemin Du Gui for about 700 m.
Turn right and follow Route de Saint-Julien for about 700 m (follow the tram rail on your left).
Turn right and follow the Route du Val d'Arve for about 900 m (this road enters a tunnel).
Turn left about 100 m after the tunnel and follow Rue Des Moraines for about 100 m.
Upon reaching a roundabout (Place Sigismond), take the next road on your right.
Follow Rue De La Fontenette for about 200 m and enter the driveway on your right.

By public transportation:
From Geneva Cornavin train station.
Take the tram n°13 (Next to Hotel Cornavin) to Place du Marché.
From this tram stop walk across Place du Marché toward the East (100m).
Then walk down Rue de Veyrier (about 300m) to Rue de la Fontenette
N°21 is in the building opposite to you on your right.