Paul Robb has a "soft spot" for historic properties. Five years ago, when he was looking for a home, he searched St. Paul's Cathedral Hill, known for its historic homes, businesses and churches.

"I've always been in love with that neighborhood," he said.

He had assumed he'd buy a Victorian-era house, similar to the two that he had owned previously in St. Paul. Instead he found an unusual urban townhouse in an old brick building on a cobblestone lane that also serves as an alley for Summit Avenue.

Originally built as the carriage house for the James J. Hill mansion, the building had been renovated and converted into four units by architect Jack Buxell.

Robb's unit, which takes up half the building, includes almost 4,000 square feet of living space. With an open floor plan and exposed original materials, "it's like a New York loft in the middle of St. Paul," he said. "Classic late 19th century industrial-style warehouse, with enormous timber frames, cast-iron fittings and a brick floor."

The home also boasts a wall of glass facing a secret courtyard, as well as a view of the St. Paul Cathedral, which is just a block away. "I can hear the bells ringing," Robb said.

His home has a tucked-away location at the end of the narrow lane. "No one knows where it is," said Robb. On his block, there aren't even street signs.

Hill built the carriage house in 1891, the same year he completed his massive limestone mansion on Summit Avenue. Why he built it a block away is unknown, but the prevailing explanation is that the site he'd originally considered, close to the house, had too steep a slope. Hill built the carriage house using brick and woodwork salvaged from his previous house in St. Paul.

The old carriage house had fallen into disrepair by the time architect Buxell acquired it in the 1980s. "It was in ruin and was going to be torn down," Robb said. Buxell spent more than two decades restoring the property.

"He put an entire new brick wall around the original structure," said Robb. "Inside is the original brick, weathered, with patina. Outside is new, pristine brick."

The home has a deep arched entry that leads to a massive copper door.

Inside is the "tack room," with original cabinets for saddles, bridles and halters. Robb restored the cabinets and uses the room as an office.

Other vestiges of the home's origins as a carriage house include a giant winch with four cables in the main living area. When Robb moved in, the cables were attached to a platform that had been used to haul up carriages and sleighs for seasonal storage. "I didn't like it dangling over my head," said Robb of the platform. "I replaced it with a big light fixture."

There's a library with bookshelves up to the second floor, and three bedrooms, which in true loft style, are not completely sealed off. "There's no completely sealed room. The master [bedroom] doesn't even have a door," Robb said.

He recently put the townhouse on the market, listed at $949,000, because he's moving out of state for his business, which produces music for film, TV and commercials. "I moved back to Minnesota for business. I'm moving out to Boston for my next location," he said.

But he's sorry to leave the townhouse. "I love it," he said. "I'm heartbroken I have to sell it. But you can't ever look at [historic homes] as your exclusive property. You pass them on in slightly better shape."

Mary Hardy, 612-751-0729, and Elspeth Hardy, 651-324-7256, Edina Realty, have the listing.