Just 17 miles north of the Mexican/U.S. border lies the waterfront city of San Diego. People come from all over the world to visit famous Balboa Park and to enjoy Southern California's world-renowned beaches. Recently rated as the fifth wealthiest city in the U.S. by Forbes magazine, it seems San Diego would leave your wallet empty. However, with all its rich history and excellent weather, San Diego is full of activities that require no cash. Here's a list of free attractions and events to get you started.