Yes, there are many castles in Europe that are free to visit, though the "level of access" varies between ruins and fully restored palaces. In many countries, you can explore the exterior grounds and certain courtyard areas of historic fortresses without paying an entrance fee. For example, the Castle of Saint George in Lisbon offers free entry to certain residents and has specific free-entry days, while many "ruined" castles along the Rhine River in Germany or in the Scottish Highlands are open to the public year-round for free exploration. Additionally, many countries offer "Free Museum Sundays"—in 2026, France, Italy, and Greece frequently open their state-run monuments, including several major castles, for free on the first Sunday of every month. In Wales, organizations like Cadw often provide free entry to their historic sites, including world-famous castles like Caernarfon or Conwy, on specific national holidays like St. David’s Day. While the "blockbuster" interior tours of places like Neuschwanstein or Windsor always require a paid ticket, a savvy traveler in 2026 can see dozens of spectacular medieval structures across Europe entirely for free by focusing on ruins or timing their visits with local cultural "open house" events.