The largest stretch of picnic greenery in Jerusalem, Gan Sacher (or Sacher Park) (pronounced Sah-kehr) is situated between the Nachlaot and Rehavia neighborhoods on one side, and the complex of government buildings and museums in Givat Ram, Gan Sacher is the largest green space in Jerusalem.
The expanse of grass is large enough that it only gets crowded during a concert, or when thousands of Israeli revelers converge on the park en masses for the annual Independence Day grill fest. The trees on the edges of the grass provide sufficient shade for a sprawling picnic spread, while the un-shaded areas are large enough to support a game of ultimate Frisbee.
More activity-specific facilities include basketball courts, soccer pitches, tennis courts, a bike path (which extends for several kilometers beyond the park), a large children’s playground, an exercise park, and the Bird Observatory. It's also a short walking distance to the Israel Museum and Bible Lands Museum. Definitely a place to go in good weather.