In Oslo it's easy to combine dining out and sightseeing. A rooftop bar is a great place to enjoy the meal overlooked by the panorama of ever-changing Oslo. The only obstacle could be the weather. Due to cooler Nordic climate, local rooftop bars operate mainly from May to September.
In fact, Oslo doesn't have too many of roof terraces but the existing ones are truly worthy. Check out the Thief Roof, Stratos, Nodee Sky at Barcode, BAR Vulkan, Q Lounge at the Grims Grenka, and Eight Rooftop Bar at the Grand Hotel.