It looks like plans are afoot to establish a new city park in the south of the city. It will be located between the train tracks and the Tuul River. Nothing has ever been built on this land because under the ground is the ground water that is used for the city drinking water. I saw some pictures of this future park. Bike paths, water fountains, gardens etc. Looks great if they can ever pull it off.
Note that the city is taking donations for this park. You can drop some togrogs in the box, which is located in the State Department Store, next to the money changer on the ground floor.