A Circle on a map will highlight a location , which covers the entire area defined as location.This tutorial will show how to Display a circle around the center location to highlight center location.

Step 1 Go to Add or Edit Map and scroll down to ‘Map’s Center’ section.
Step 2(Optional) Assign center latitude and longitude to the map. By default, center location is automatically calculated based on locations assigned to the map.
Step 3 Then Enable ‘Display Circle’ tab to display circle around center location.
 
Center location circle

Step 4 Then click on Save map.

Now you’ll see circle around center location.
 
Center Circle

Video Tutorial