How do I rotate the city?

Yeah that sucks. Short answer is, you can't. You gotta move what's obscuring it first, then move the park.

Unfortunately, you can not "rotate" the view. However, if you click-hold on a building near the park that you want to move, you will see a grayscale picture of your city and in the lower right-hand side is a down arrow pointing to two yellow rectangles. Click on this "flatten" button to change all building into flat boxes in your city. Click on the red "X" to leave the building near the park where it is. Click-hold on the park to move it.