Rosersberg Palace is one of the Royal Palaces of Sweden. Situated on the shores of Lake Mälaren, on the outskirts of Stockholm, it was built by the Oxenstierna family and became a royal palace in 1762, when the state gave it to Duke Karl (later Karl XIII) the younger brother of Gustav III of Sweden. Construction of the building in the typical Renaissance style of the time started in 1634 and was completed in 1638. It was later radically modernized in the then current Rococo style under the architect Nicodemus Tessin the Younger.