Every space that has an AED should have it clearly marked with a green-and-white AED symbol (a heart with a lightning bolt), usually near a main entrance, front desk, or central hallway.
Take a moment now, before there's ever an emergency, to actually locate the AED in any space you spend regular time in - an arena, a community centre, a workplace, a school.
Many AED cabinets have an alarm that sounds when opened. Don't let that stop you from using it if someone needs it - the alarm is meant to draw attention and help, not to discourage use.