Zagreb-based architectural office PROARH completed Issa Megaron, a family retreat in Croatia that’s disguised inside a Rocky hillside with a zigzagging road. Due to its remote location and lack of surrounding infrastructure, the contemporary home operates off the grid by necessity and includes self-sustaining technologies from rainwater collection tanks to solar photovoltaic panels. Going off grid, however, hasn’t compromised the architect’s pursuit of luxurious living, made evident by the…