Inside the Prague Castle (Prazsky Hrad), there is Prague Castle Gallery that hides in a small building that you can easily miss. I highly recommend visiting this gallery. Not only will you see works by Czech baroque masters like Kupecky, Spranger, and Skreda that are mostly unknown until you come to the Czech Republic and visit several museums and churches, but you’ll also see a collection of European masters of the 16th and 17th centuries. Dutch and German masters are well represented by works of Rubens, van Cleve, Holbein the Younger, and Cranach the Elder ("St Catherine and St Barbara" alone make it worthwhile coming to the gallery). Italian school is also not bad—there are paintings by Reni, Massari, Tintoretto, Schiavone, Bassano, and Veronese’s striking portraits and religious scenes, Titian’s "Madonna and Child with Young John the Baptist" is not only an amazing painting but also has a wonderfully original frame. There is also Titian’s "Young Woman At Her Toilet", which very much reminds me of his painting of Diana (in London). The major drawback is bad lighting and the brick color of the walls.