For those who have had a desire to stay overnight in an igloo, perhaps consider the Hotel Kakslauttanen in Finland. This glass hotel consists of 20 separate thermal glass igloos.
These igloos offer very clear views of the sky -- perfect for star gazers and those interested in viewing the Northern Lights. Each room contains thermal glass walls and ceilings that allow for optimal viewing and warmth. The insulated glass prevents frost from developing and will keep you warm in the -22 Farenheit weather. Each room also contains a luxury toilet and beds.
These hotels are located 250 km above the Arctic Circle so prepare for some cold nights if you venture out of Hotel Kakslauttanen. However, the hotel also boasts the largest smoke sauna in the world -- so it might not be so bad after all.