Where is my object "dimensions" control? Title says it, where is the "Dimensions" control?

I know I'm supposed to be in "Object" mode (I am, see screenshot).
The dimensions of your object can be found in the properties panel. To bring up that panel either click on the little '+' icon at the top right of the 3d view or hit N with your mouse above the 3d view. The dimensions are located under the Transform heading.