Prague will most likely be the place where you'll start your vacation in Czech Republic and a great place for sightseeing. The center of Prague has a lot of history with famous monuments such as the Astronomical Clock, Charles Bridge, and Prague Castle). A few other places to visit are Olomouc, Cesky Krumlov Castle, and The Macocha Caves which are home to an underground river. The caves are open for tours, which also includes a boat ride on the river.
Czech Republic is stunning and Prague alone is a jewel, but you must make an effort to see the rest of the country. My favourite places in the Czech Republic are Spindleruv mlyn, Hradec Kralove and Podebrady.