When you enter the century-old Carnegie library that houses the National Music Museum, your first impulse might be to wonder why there’s a cannon in the lobby. Upon further review, it turns out to be a 10-foot-long, 1,000-pound Thai drum, mounted on a carriage for easier transport.

And that’s your first clue that this museum is brimming with things you’ll never see anywhere else.

The museum, set in the heart of the University of South Dakota campus in the prairie town of Vermillion, is considered one of the world’s top three or four collections of rare musical instruments. The 15,000 or so instruments in the collection (about 1,200 of which are on display) are rife with descriptors such as “first,” “oldest,” “best” and “only.”

This charming old building bursts with treasures, such as the world’s oldest cello. The oldest playable harpsichord. One of two existing mandolins crafted by the legendary Antonio Stradivari, and one of five guitars made by him. They have Stradivarius and Amati violins and violas.

The museum has more than a dozen saxophones made by the instrument’s inventor, Adolphe Sax. There are trombones with so many twisting tubes that they look like a Dr. Seuss creation. Harmonicas so small you could fit them on a postage stamp.

There are instruments that once were common but are now obsolete: lutes, citterns and a bombardon, a bass tuba that looks like only a giant would have the lung power to get a sound out of it. There are bouzoukis and nyckel­harpas and hurdy-gurdies. In short, it might be easier to name something they don’t have.

Renaissance to Dylan

The question that naturally arises is: How did this world-class collection of instruments — worth tens, if not hundreds of millions of dollars — wind up in South Dakota’s 11th-largest city, a community an hour south of Sioux Falls whose charming old Main Street extends for only four or five blocks?

It began with Arne B. Larson, a native of Hanska, Minn., who wound up as a high school band director in Brookings, S.D. He also pursued old band instruments, spending his free time searching attics and barns for rare examples.

“He sort of was the essential hoarder,” said Patricia Bornhofen, the museum’s manager of communications. By the early 1970s, with his collection having grown to thousands of instruments, Larson sought a home for it. In 1973, the university agreed to give him a room in its old library. Eventually the museum took over the whole place.

Its real growth came under Larson’s son, Andre, who became the museum’s first director. Andre Larson tapped into South Dakota’s small cadre of wealthy residents and convinced them that the museum was worthy of their support. “They pooled money and purchased some collections that would be untouchable now,” Bornhofen said.

The museum won’t comment on the value of its holdings, but Bornhofen pointed out that a Stradivarius violin sold at auction five years ago for $15.9 million.

A visitor could easily spend an entire day wandering through the closely packed exhibits, which are informatively labeled. The two-story building isn’t small by any means, yet it’s stunning nonetheless just how many treasures are packed into the place.

The museum employs about 20 people, including conservators who perform upkeep and restoration on the instruments. It’s a complex job; in addition to their age and frailty, many of the lavishly detailed instruments feature intricate carvings and inlays of precious wood, metal and jewels.

In the Rawlins Gallery, the museum features one of the greatest collections of Renaissance stringed instruments in the world. In addition to its Stradivarius and Amati violins, the gallery displays the “King” Cello, an Andrea Amati creation dating from about 1550 that’s the oldest cello in the world. It was built in Amati’s workshop in Cremona, Italy, and later painted and gilded as part of a set of instruments for King Charles IX of France.

“This is the Mona Lisa of our collection,” Bornhofen said.

An adjoining gallery features a guitar collection including a Martin flat-top that’s a gift from singer Shawn Colvin, a Vermillion native, and a Villar guitar owned by Bob Dylan that he used to compose many of his early songs. The guitar gallery also includes the actual workshop of renowned 20th-century guitar makers John D’Aquisto and John D’Angelico, as well as a Rickenbacker “frying pan” that’s one of the earliest electric guitars.

‘Sky’s the limit’

The museum is hoping to expand its space, said Cleveland Johnson, its director. And that means expanding its range of supporters.

“The museum has been built on the shoulders of very loyal folks close to home,” Johnson said. “These people were all about creating something that would be a shining example of culture here on the prairie. It’s a fascinating convergence of serendipity and fate.

“The collection has untapped potential to attract people,” he said. “The sky’s the limit on who wants to see a roomful of Italian violins.”

Still, he added, “If you were trying to decide strategically where to locate a major museum collection like ours ... ” letting the thought hang. “It’s a real incongruity.”

The museum hopes to raise $4 million to take over a neighboring building and build an atrium connecting the two structures. And Johnson would be thrilled to get more visitors from the Twin Cities.

“This is the perfect day trip or weekend trip,” he said, adding that Chicago, Kansas City-Omaha, Denver and St. Louis are also logical target markets.

In addition to the instruments’ beauty, Johnson said, he finds them fascinating as examples of technology.

“So much innovation today is out of sight. You can’t see it, much less understand it,” he said. “This is very sophisticated technology. Musical instruments are tools, and toolmaking is kind of what makes us human.

“Someone had to design them. Someone had to build them. Look at a violin. How the hell did someone come up with that?”

Johnson said he hopes to feature more information about the instruments’ engineering, as well as more interactive attractions.

In the meantime, if you love music, or history, or marveling at craftsmanship and handiwork, the old library in Vermillion is well worth a visit.

That Amati cello traveled five centuries and thousands of miles to its home on the prairie. You can get there in a morning.

More info

The National Music Museum is open daily (except for Sundays from September through May). Admission is $10. Info: nmmusd.org.