Havlíčkovy sady aka Grébovka is one of my favorite parks in Prague. You can go there and have a picnic (when it is warm of course), walk your dog, do some jogging or even have a glass of local wine…
Parents with kids will find two playgrounds in the park, one of them is right below the wine cellar (see below). In autumn, it is a great spot to collect fallen colored leaves and chestnuts. Now in spring, you can observe young squirrels running and jumping from one tree to another.
The park was built between 1871-1888 around a villa which belonged to Mr. Moritz Grobe (an important Prague industrialist of his time). You can find many interesting things in Grébovka: the above mentioned villa, an artificial cave (grotto), an ex “gaming house” (and there is a restaurant now).
There is also a wine cellar, opened each Friday from 14:00 till 21:00.