Vilnius University is one of the oldest universities in Eastern Europe, founded in 1579. Its campus occupies a significant portion of the old town — 13 interconnected courtyards of varying sizes surrounded by buildings spanning four centuries of architectural styles, from Renaissance to Baroque to Neoclassical. The university is still an active institution, and most of the buildings are open to visitors during the day.
The highlight is the Church of St. Johns (Šv. Jonų bažnyčia), whose interior was gradually decorated over 200 years with Baroque frescoes, altars, and ornament. The library and the main Sarbievijus courtyard are also worth seeking out. The university bookshop in the complex is one of the better ones in Vilnius. Entry to the courtyards is free; some buildings charge a small admission.