The roots of what we now know as the National Library go back to the days of King Gustav Vasa in the 16th century. The king collected books on a variety of subjects including history, science, and theology, as well as maps. The collections were expanded by Eric XIV, Johan III, and Charles IX and kept in the palace known as Tre Kronor (The Three Crowns). Some books were purchased abroad, while others were confiscated from Swedish monasteries dissolved in the Protestant Reformation. King Gustavus Adolphus gave away parts of the royal book collection in 1620: those books were the foundation of the Uppsala University Library.