Stone Mountain a little outside of Atlanta, think its something like 2000 feet high. And a few years back I went to Glorietta, New Mexico and it was at an elevation of 7000+ ft. I'm used to 20 foot elevation air so it was really wierd way up there. I'm very athletic but would sometimes get short of breath just running up several flights of stair to get to the lunchroom, especially when the air was cold! After a week I got used to it though :P