Royal Game Park, locally known as Stromovka, is a large park situated in the heart of the city. The name reflects the original purpose of this area, which served as a game reserve in the 13th century. This park is now a well-facilitated oasis of peace with many playgrounds as well as picnic sites.
Open 24/7.
Wikipedia https://en.wikipedia.org/wiki/Stromovka
More information http://www.prague.eu/en/object/places/483/royal-game-reserve-stromovka?back=1
Coordinates 50°6'22.824" N 14°25'6.936" E