Atlantic City has always been primarily a resort town. Atlantic City became a popular beach destination because of its proximity to Philadelphia.

In 1870 the first boardwalk was built along a portion of the beach to help hotel owners keep sand out of their lobbies. The idea caught on, and the boardwalk was expanded and modified several times in the following years. Today, it is several miles (kilometers) long and sixty feet (twenty meters) wide, reinforced with steel and concrete. It is now the world's longest boardwalk.

In an effort at revitalizing the city, New Jersey voters in 1976 approved casino gambling for the city of Atlantic City. Resorts International became the first legal casino in the eastern United States when it opened on May 26, 1978. Other casinos were soon added along the boardwalk and later in the marina district for a total of twelve today. Another major attraction is the oldest remaining Ripley's Believe It or Not! Odditorium in the world. It is also Ripley's most famous odditorium.

Information above provided by Wikipedia.