The famous Icehotel. Surely it's one of the most unique hotel in the World. The idea is very creative and beautiful and it's a must to visit there if you are near to Icehotel. The accommodation is very expensive but you can always visit there as a museum. There are two types of room; luxury and standard. Each luxury room has a unique design and there is a ice sculpture inside of it that is created by various talented artist around the World. Icehotel also has a unique Church and Bar. It's built from ice blocks from Torne River. They mixed up snow and ice for the construction material and they call it "snice". Ice blocks are very clear and smooth. The temperature is there between minus 1 to 5 degrees but you don't feel that much cold because you are well dressed with overalls.
I went there with a Snowmobile tour and it was a great fun too.