You think you may be a little off course, but you're close to your destination airport, so you begin looking for the familiar scar of a runway against the ground. You spot a runway off to your left, and you turn toward it. You dial in the unicom frequency for your destination and announce your position and intentions. No one answers. That's not so odd; it's a small field and the operator may have stepped away. There's no one in the pattern so you enter the 45. But wait. You'd better be sure to take a good, hard look at this airport before you land.
Turns out, you're in the wrong place. This airport is closed and has been for some time. But how do you know? First there's the runway itself. The large X painted on each end indicates that it's closed. If you get close enough, chances are that you'll also see some potholes or other damage to the pavement.
Second, there's the chart. The airport is marked as an open magenta circle with an X through it. It does not have an identification box with the airport name, three-letter identifier, communication frequencies, or other information. This symbol means that the airport is closed but has a paved runway that is at least 3,000 feet long.
But why show an abandoned airport at all? Closed airports, especially those with long, paved runways, make great landmarks. Depending on their condition, they may even make good forced landing sites.