The Teener building, middle, was built in 1922. The Brave New Workshop signed a purchase agreement on the building to expand its downtown Minneapolis presence. (Star Tribune/The Minnesota Star Tribune)

Sketch comedy can mean serious business.

Brave New Workshop, the nation's oldest improv comedy troupe, known for shows with such titles as "Sex in the Cities: The Edina Monologues" and "How to Make Love Like a Minnesotan III: The Full Montevideo!," has embarked on a multimillion-dollar expansion in the heart of Minneapolis' downtown theater district.

The 55-year-old company, whose alumni include Louie Anderson, Lizz Winstead, Melissa Peterman and Al Franken, has signed an agreement to purchase 727 Hennepin Av. S., a building that formerly housed Teener's Theatrical Costume shop and is currently home to Unbank, officials said Monday.

Terms of the sale were not disclosed. The narrow 1922 building is by Magney and Tusler, who also designed the Foshay Tower and the downtown post office. Sandwiched between buildings that house Bar Fly and Union restaurant, it has nearly 20,000 square feet. Recent transactions in nearby downtown real estate have been in the range of $100 to $150 per square foot.

The workshop plans to use the Teener building for its school and offices, while continuing public performances at its main stage on the other side of Hennepin in the next block.

The latest deal continues the workshop's rapid growth since 1997, when John Sweeney and Jenni Lilledahl, who also are married, bought it from founder Dudley Riggs. The annual budget then was $250,000. Today, it is $3 million, said Sweeney.

In April 2011, the workshop bought the former Hey City Theatre at 824 Hennepin Av. S., which has 206 seats, and relocated its main stage there. While it retained much of its Uptown audience, it was also able to attract convention-goers, Twins fans and others in the high-traffic downtown corridor.

"The idea for our cultural district is that we weave together all the aspects of the avenue with arts and culture," said Thomas Hoch, president and CEO of Hennepin Theatre Trust, which has four theaters on Hennepin. "The Brave New Workshop is a very important, super-exciting part of that."

The workshop's success is a rarity in commercial entertainment, which often is a money-losing proposal. The late Twin Cities philanthropist and entertainment mogul Jim Binger, who owned five commercial theaters on Broadway, often joked that the best way to get to a million dollars in for-profit theater is to start with $10 million.

The company has profited from a business model that includes a school, its main stage offerings, space rental and corporate training.

"If you would've asked me two years ago if we would have nearly 40,000 square feet of downtown real estate, I would've told you that you were crazy," Sweeney said Monday. "But this ensures that we can do improv downtown and take it to the world."

Rohan Preston • 612-673-4390