This may come as a bit of a shock, but if you live in a city (or any area with a lot of buildings and not a lot of trees), spending time in nature is really, really good for you.
With that in mind, here are a bunch of city parks around the world that are worth taking a detour to if you're in the area:
1.Stanley Park, Vancouver
2.Smale Park, Cincinnati
3.Parque de Los Pies Descalzos, Medellin, Colombia