Rembrandt, Vermeer, and Degas, where art thou? That’s a question the staff has been asking at the Isabella Stewart Gardner Museum since 1990, when thieves made off with 13 of the museum’s most valuable pieces, worth an estimated half a billion dollars. Rather than sulk, however, museum officials left empty frames on display both to educate visitors and to serve as hopeful placeholders awaiting the artworks’ eventual return. Meanwhile, you can visit the museum’s lovely courtyard and vast collection of historic and contemporary art at Fenway Court, built to resemble a Venetian palazzo and packed with paintings, sculpture, furniture, and textiles gathered by Gardner, an avid art collector and philanthropist, during her lifetime. Pro tip: Wear a Red Sox hat or shirt to get a $2 discount on admission—as stipulated by Gardner after her beloved Sox won the 1912 World Series (also, you get in free if your name is Isabella).