Biggest castle in Europe! Beautiful views of Prague from here. History is so well preserved.

The largest castle according to the Guinness book of records, with the large St. Vitus cathedral in the middle. It's too bad that the original gothic architecture of the buildings is mostly obscured by the facades placed during renovations ordered by Maria Theresa, but St. Vitus cathedral and other structures show their bare beauty. It is highly recommended to take a tour through the castle if you care at all about information on it as there is almost nothing available, not even in Czech. Another sight near the castle is the changing out the guard outside of the original gate at every hour. The most important change is said to be at noon.

Entrance to the grounds are free. Entrance to everything else costs money (tickets span two days, but only one entry to each thing). I found the St. Vitus's Cathedral tower to be fantastic, along with the "Story of Prague Castle" exhibit, though the Old Royal Palace and Rosenberg Palace were pretty bare bones. St. George's Basilica was fine, but if you've hit up a bunch of churches, it's one you can skip. St. Vitus's Cathedral, on the other hand was absolutely beautiful inside. The Golden Lane was okay, if you're interested in seeing the tiny homes/work spaces people used to have. Daliborka Tower was interesting, and worth seeing.