Riells I Viabrea is a town in La Selva - Girona, Catalonia between Sant Celoni I Hostalrich The name '"Riells'" is derived from the four streams that go underground. In the 1960s, Riells was little more than a wood with a lake between Montgó, itself much smaller than it is today, and el Poble Sec. Housing construction began in the 1970s.