The beautiful nature of the Ukonniemi region on the shore of Lake Saimaa was still a forested area in the 1930s, which was led only by horse-drawn carriages and pebbles used by landowners, fishermen and sandy swimmers. As early as 1930, the Board of Imatra Workers ‘College considered a summer vacation place to be established in Ukonniemi, but only in 1938 they got the promision from the Workers’ Association to built up a summer place. Ruokolahti owned the farm whose lands had to be built on for summer vacation, so the land was rented from Ruokolahti. Ukonlinna was completed in 1939 largely by the student workforce. The funky, lush-like appearance of Ukonlinna has been drawn up by Master Urho Räsänen, and the building has been called Ukonlinna sens that day. In 1955, electricity was delivered to the castle and the following year the phone. The dance floor in Ukonlinna’s yard was completed in 1958, which was rebuilt and covered in 1999. This dance floor has several summer dances, weddings and midsummer dancing.
The renovation work was carried out in 1966 when the kitchen and sauna were enlarged and the covered terrace of Ukonlinna facade was built. In 1945, the Workers’ College rented Ukonlinna to Tainionkosken Tähti ry and in 1949 the ownership changed to Tähti altogether. For two years Ukonlinna was used as a summer home for members of the club, but this changed in a couple of years when foreign guests began to visit the castle. In the winter of 1949 Ukonlinna again experienced a new change when the castle was started to bee jused as a skicottage in the winter time. A new paint job was also given in 1954, when Ukonlinna was painted from outside and from inside. At the same time, the dining room was painted as well. The walls got a pictures of the diferent sports that have been taken by the Tainionkosken Tähti ry. The paintings were made by Aatos Hasu and Veikko Lampinen and they are still in there former glory on the walls of the diningroom.
In 1954, Tainionkosken Tähti ry joined the Finnish hostel association and Ukonlinna became a hostel for the area. Ukonlinna has been operating since then all year round: in winter as a skicottage and in the summer as serving a refreshing drinks for the people on the beach. Today Ukonlinna is a popular hostel with a large number of international and Finnish visitors annually.