Petrin is one of the largest green spaces with superb views of Prague. It is just south of Hradcany from where numerous paths lead uphill. But there is no need to walk all the way as the funicular railway will take you up. It starts at Ujezd (U Lanove Drahy), at the same price as a tram ride. The same ticket can be used.
On top of Petrin hill is Petrin Tower built in 1891 for the Prague Exposition. It is a 60m-tall Eiffel Tower look-alike and offers outstanding views of Prague. As climbing the 299 steps is slightly strenuous it is probably best to wait for a clear day to tackle the climb.
Address:
Petrin Hill / Park Prague Hlavni Mesto Praha Czech Republic