You’d think that a building big enough to hold a couple dozen Mack trucks would be easy to find. Uh-uh. The Mack Trucks Museum is hidden away on the back side of Allentown’s Queen City Airport, nestled on a hilltop overlooking the scenic Lehigh Parkway.

There’s a reason for the subterfuge that makes finding this gem a little like participating in a road rally where you have to find and follow clues to reach the prize – it used to be the Test Center and Track where Mack developed their new models and put them through a series of real-life situations to ensure that the customer was getting a product that had been road-tested.

This vintage Mack Truck from the early days of the 20th Century greets visitors in the Heritage Center.

Today it also serves as the Customer Center, where potential buyers are awed not only by the massive Macks on display but by the history of a company that is as tied to Allentown as A-Treat soda and the old Hess’s Department Store.

Open only three days a week, the museum saw more than 5,000 visitors last year. It consists of three separate wings, the Heritage Center, the Mack Museum itself, and the Product Showroom.

The Heritage Center highlights the history of the company and explains the origins of the iconic bulldog hood ornament, along with displays that include the 1900 Mack Touring Bus with wooden wheels, solid rubber tires and a chain drive that was used to take tourists around cities such as New Orleans and Chicago at speeds of up to 15 mph. Really.

The timeline along the back wall explains how four of five brothers from Scranton started their motor-vehicle manufacturing in New York City before Joseph told Gus and Jack about a great building in Allentown that would suit their growing needs. In a nod to Mack’s penchant for preservation, the room includes the grandfather clock and safe from Jack Mack’s office.

“It’s kind of amazing for the age of the company, how much was kept and passed along,” said tour guide Don Seifert, a 34-year Mack veteran who was laid off when Volvo moved the corporate headquarters to Greensboro, N.C.

Seifert explains that the bulldog ornament was developed in tribute to British soldiers in World War I, who came to depend on the indomitable nature of their Mack AB trucks – with their unusual pointed hoods created by putting the radiator behind the engine — so much on the front lines that they compared them to the classic British pets. The bulldog became an official ornament in 1942.

The Production Showroom is actually a customer display center, featuring the various modern Mack lines such as the over-the-road Titan tractor and heavy-duty construction Pinnacle dump truck. But it holds a couple of neat surprises, like the original Megatron from the Transformers movies.

Once you get to the actual museum, make sure to visit the enormous, two-story Sound Room, which includes about a dozen classic Macks from decades past, such as a 1958 fire truck and a 1963 delivery truck. All are on-loan from private owners and members of the Antique Truck Club of America.

The Sound Room, or Acoustics Room, is a must-see for visitors.

The sound room was a hit with Alex Lingle, a 15-year-old home school student touring the museum with his family. “It’s really cool,” he said. “I really liked the Showroom. They had some neat trucks in there.”

His brother, Jared, 12, was thrilled by the countless exhibits of toy trucks in showcases in the museum wing but also enjoyed seeing Megatron and learning about how Mack works with the movie industry.

“It was impressive,” said their mother, Michelle Lingle. “As a woman, I recommend going. The history is really impressive and the showroom was something else.”

If You Go: The Mack Museum is only open Monday, Wednesday and Friday from 10 a.m. to 4 p.m. Admission is free, but all tours are guided. Parking is available. For tour information, call 610-351-8999.

What To Know: The Mack Museum and America On Wheels in Allentown make a great double-header for motorheads and families.

Fact: The Mack company began in 1893 when Jack and Gus Mack bought a carriage buildier in Brooklyn. They were later joined by brothers Willie and Joe. By 1912, all four of the Mack brothers had sold their interest in the company, which retains their family name a century later.

Update: The Mack Museum and Mack Macungie Assembly Plant will be open for tours on Saturday, June 16. Click here for more information.