If it is not a complete circle, but a partial circle around an upper-case "A", similar to the partial circle around a lower-case "a" that comprises the symbol @, then it may represent atheist or Atheism. In this usage, it is often depicted in red.
national capital city
right round a circle
Four Letters Capital
It is an instrument that tells you which direction is north, or a tool for drawing a circle. It can also mean range.
To make a complete change
A star is a capital and a circle is a city
a capital
This shows the capital or national capital
it means a capital
capital city
capital city
it means the national capital on a map
a state capital
a state capital
a state capital
Circle with a star in it will often be a State/Province capital.
On a map, a star usually marks the capital of the state, province, or country. A dot in a circle usually marks other major cities.