Atlanta is in the HEART of
Georgia and is crossed by three interstates: I-75, I-85, and
I-20 which all connect with the circular I-285 that goes all the way
around the city. It is also known as The Perimeter
roadway.
Atlantans give directions based
on the Perimeter and say whether they live inside the perimeter (ITP)
or outside the perimeter (OTP). When giving directions they
say, Take the Northeast expressway (that's I-85) to spaghetti
junction then take the first exit "outside the perimeter"
(that would be Pleasantdale) or they say take I-20 past Six-Flags to
"inside the
perimeter" to get to the King Center or the state
capitol.
The thing you have to understand
is that "inside the perimeter" can mean any direction
depending on where you are at the time. Another trick is to
imagine that the perimeter is the face of a clock and find out if
you need to go to "six o'clock" to get to the airport or
"eleven o'clock" to get to Smyrna.
Then there is the inner and there is the outer loop. What do I need to say about these? The inner loop is 285 going clockwise if you are looking at the city from the south with the city center as the middle of the clock and GA 400 as twelve o'clock--and the outer loop goes counterclockwise on the same clockface? Both loops go in all directions (but only one direction at a time) depending on whether you are at 6 o'clock or 12 etc.
So, for example, if you are at 6 o'clock (down near the airport in the South) and you are on the inner loop, you will be traveling west--if you are on the outer loop you will be traveling east. If you are at 9 o'clock (near Six Flags where I-20 comes in from Alabama) and you are on the inner loop, you will be traveling north. But, of course, if you are at spaghetti junction where I-85 and I-285 intersect in northeast Atlanta and where the inner loop can take you inside the perimeter or outside the perimeter you will be so confused that it won't really matter what direction you are going--just be sure you know if you want to go to Atlanta or to Greenville, S.C. and follow the signs to that city.

Spaghetti Junction looking Northeast, cars coming toward us are going to Atlanta on I-85.