With summer vacations over and students back in school, the crowds are thinning at Universal Studios Park in Hollywood, California. But not by much. The movie-studio theme park, open since 1964, is one of the most popular year-round tourist destinations in the United States.

Universal Studios is the home of one of the biggest and busiest working motion picture studio in the world. To tour the studio and its 400 plus-acres theme park, is to be immersed completely in the excitement of Hollywood's make believe worlds.

Visitors are surrounded by movie history, live action shows, movie stunts and visual tricks performed by special effects experts.

Universal Studios' Bates motel was the local for "Psycho"

Rick Fitzgerald is a veteran Universal Studios tour guide. "Because of its history, because of what it offers, guests have the opportunity to go right on the back lot to see filming going on. We drive them onto the most famous sets in Hollywood history. Sets from films like Jurassic Park and Alfred Hitchcock's 'Psycho.' "

As guests tour the Hollywood sets they sometimes get to see their favorite stars actually at work filming their next movie.

Universal Studios, Jurassic Park

Another unique thrill is the chance to walk around in the actual environment of blockbuster adventure movies like "Jurassic Park".

Director and producer Steven Spielberg says he knew from the start that his dinosaur movie would fit right into the theme Park. "We began the concept of Jurassic Park -- the ride -- while Jurassic Park -- the film -- was in production."

Another popular draw at Universal Studios Park is the "Terminator", based on the trio of science fiction films about killer robots. Academy award-winning director James Cameron says the park takes the movie to a whole new level. "We are trying to break down that barrier between the audience and the film through actually having characters jumping into the screen and come down from the screen."

The special effects stages reveal the production secrets behind the scenes of some of Hollywood's blockbusters including the "Star Trek" series and "The Mummy Returns."

Visitors also get to see how fist-fighting scenes are choreographed, how spectacular explosions are detonated safely, and how a stuntman survives a plunge from a tall building.  And daring jet ski operators wow the crowds in the Park's popular Water World.

Norm Kahn is Water World spokesman. "[It is] spectacular for the audience, because not only they do see the explosions, the fights and the high fall, but they also see spectacular stunts on jet skies and water skies"

It's not uncommon to spot some Hollywood movie stars sharing the fun at the park. Here, Brendan Fraser is reliving his hit movie "The Mummy Returns" -- not acting in it but just going along for the ride. "It is great, it is in the spirit of the film, which is adventurous, fun, like some other rides. It does not take itself so seriously, but it is formidably frightening when it needs to be."

Universal Studios started its "Behind the Scene Tram Tour" on July 1964.  Since then, over 100 million people have been entertained -- and educated -- at one of Hollywood's most historic studio lots.