Plante paid $4.1 million for the 18,214-square-foot building at 1433 17th St. He bought it recently from the Cage Williams Abelman law firm, which will lease back the property until it determines where to relocate.

"They decided to put the property on the market to take advantage of some of the market conditions," said Darrin Revious, a broker with Frederick Ross who represented the firm.

Plante plans to restore the building's facade and list it on the National Register of Historic Places. He wants to start work in the next few months and finish the renovations by early winter.

"It's one of those quintessential buildings in LoDo that's unlike any other," Plante said. "It's a corner (17th and Market streets), and it's unique in its size and appearance."

Plante will present his plans to the LoDo Design Review Board on April 5.

When it was built in 1896, the St. Elmo Hotel joined a plethora of small hotels clustered in LoDo to serve railroad travelers. It remained a hotel well into the 20th century, then stood vacant for a number of years.

When it was renovated in the 1980s, the building's first-floor facade was removed and garden- level windows were built in. Over the years, it has housed oil firms, small businesses and law firms.

Plante also has completed historic renovations on Platte Street, including the A.H. Root Building, home to Sushi Sasa, and the Zang Building at the base of the new Highland Bridge.