The town of Sonlerto lies in Bavona Valley (Val Bavona), arguably the wildest one among the valleys of Ticino. This spectacular side valley is part of the Maggia Valley. The whole region is part of the Lepontine Alps – a mountain range that covers various parts of Switzerland (Valais, Ticino, Uri, Graubünden) and Italy (Piedmont and Lombardy).

The Bavona Valley has seen massive rocks fall from mountains time and time again. Sometimes the stones are as big as houses. Locals then build new houses next to the stones after they fall. Locals refer to it as Splui. As such, it is no surprise that the houses in this area are built from stone.