Click on the Status and Reports button  on the top of the toolbar to bring up a list of status reports. That list shows a Civilian Roster, an Army Roster and a Navy Roster. Each Roster shows a list of all your units in that category. You can click on a unit in the roster to close the roster and center the map over that unit. 

There is also a Development Roster which shows a list of all the tiles you have developed with the Builder. 

These rosters are useful for quickly checking on whether any units or developments should be upgraded. The keyboard shortcuts to them are: F9 Development Roster, F10 Army Roster, F11 Navy Roster, and F12 Civilian Roster.