The smell of pizza hangs heavy in the air when the evening train pulls into Organ Stop Pizza in Mesa, Ariz.

Vibrations, at first soft and finally overbearing, shake the rafters and wiggle the beer suds throughout this 800-seat restaurant, mostly filled on this warm February night with retired Northerners defrosting for a few months in the Valley of the Sun.

Their eyes widen as the rumble rolls closer, a few checking their fillings, mouthfuls of mozzarella on standby for the moment. But Lew Williams isn’t worried. He’s been conducting this locomotive for the better part of 18 years, and he hasn’t derailed yet.

The roar changes to a CHUG!, and then another, a few more, faster, and finally, Williams rips another rendition of “Chattanooga Choo Choo” out of his organ console. He’s yet to play the song the same way twice, or any other tune for that matter, which is just fine with him. After all, friends and music critics, this is the greatest theater organ show on Earth, and it is about much more than music. As Williams himself likes to put it, if the classical organ is Luciano Pavarotti, then this baby, with all of its additional bells and whistles (literally), is somewhere closer to Garth Brooks.

From the outside, Organ Stop feels church-like with its symmetrical, three-tiered architecture, and its style of worship points toward Pentecostal (with extra pepperoni, please) once the glass front that houses the organ’s largest pipes comes into view; the turbine-powered pipes, all brightly colored, include some 32 feet tall. Said Williams, “It looks like the world’s largest box of Crayons.”

Inside, there is Organ Stop’s centerpiece itself, a 1927 Wurlitzer organ, second-largest in the world. The 5,000-pipe ebony console, gold-leaf accents on all sides, has 422 stop keys and 100 pistons; an offstage computer can change the sounds for each one of those keys 99 times.

But then there’s the other, uh, stuff. The grand piano, controlled remotely, as well as a saloon piano. The complete range of trumpets along the back wall. And the wind chimes. The sleigh bells. Tambourines. Castanets. Snare drums. Bongos. A fire engine horn. “Ooogah” horn. Tweety Bird pipe. That is not a complete list. For special effects, there is a kaleidoscope projector, a disco ball, strobe lights, soap bubbles that drop from the ceiling, and, the personal favorite for most patrons, four dancing kitties controlled from the organ’s pedals and keyboard.

And Williams modestly confesses to being the “musical centipede” who controls it all — at least on his shift, Charlie Balogh being the other staff organist — which is almost as impressive as the music repertoire Williams plays, all from memory.

The top request is a medley from Phantom of the Opera, but lately Elton John’s “Candle in the Wind” has also been in demand, as well as the theme music from Titanic. Other mainstays are the “Battle Hymn of the Republic,” “Lara’s Theme” from Dr. Zhivago, the theme tune to TV’s Mission Impossible, the finale to the “William Tell Overture” and any state song from the North, including “Yankee Doodle.” (He’ll also sneak in the “TCU Fight Song” or Alma Mater for any Horned Frogs in the crowd.) Of course, Williams will also play Beethoven and the like, but perhaps as you’ve never heard it, or seen it, before.

Indeed, Williams has been all over the country and in England performing in venues where staying true to the score is the whole point. His accolades, including his 1988 honor as Organist of the Year by the American Theatre Organ Society, indicates he’s pretty good at it, too. But this venue doesn’t demand anything other than entertainment, and so that’s why Williams, at least once every night, comes by in his train and tries to get as many as possible to come aboard.

“At any given time, there are people up there who couldn’t care less what I’m playing,” Williams said. “But I’m also playing to people who perhaps have never heard an organ or who have never heard classical music before.

“That’s who I’m playing for.”