If it's a picture-book European castle you're after, look no further. Perched atop a wooded hillside, Karlštejn comes complete with battlements, turrets, and towers. Once Charles IV's summer palace, Karlštejn was originally built to hold and guard the crown jewels (which were moved to Prague Castle's St. Vitus's Cathedral in 1619). There is a fairly strenuous hike up to the castle—lined with souvenir stands and overpriced snack bars—but it's worth the journey. Once you've reached the top, take time to walk the ramparts and drink in the panorama of the village and countryside below. There's a slightly bewildering list of different interior tours, but the pick of the bunch is tour number two, which includes the castle's greatest treasure, the Chapel of the Holy Cross, which once held the crown jewels. Tours of the chapel are limited (and more expensive than the other tour route), so you must book in advance. There's an exterior tour too if it's a sunny day, or you can poke your head around the exterior courtyards at no cost. Because of its proximity to Prague, it is the most-visited site outside of the Czech capital, so be prepared for crowds, especially in the high summer months.