A plan for a seven-story apartment and office building at the northeast corner of Ninth and New Hampshire streets has won a key City Hall approval.

The city’s Historic Resources Commission on Thursday night gave unanimous approval to the design of a 121-unit apartment building proposed by Lawrence businessmen Doug Compton and Mike Treanor.

But plans to install a roundabout at the busy Ninth and New Hampshire intersection are still uncertain. Members of the Historic Resources Commission said that decision is best left for the City Commission.

Developers of the proposed multistory building said they were pleased with the outcome.

“We think it is going to be fantastic for downtown,” said Bill Fleming, a Lawrence attorney who represents the development group.

The building — proposed to range in height from 77 feet to 68 feet tall — will have its design further reviewed by the city’s Architectural Review Committee, but the city’s historic resources planner said that review mainly will focus on technical issues such as the type of materials used in construction. She said the major issues of whether the building was too tall or damaged the historic character of the downtown have been settled.

“The discussions with the Architectural Review Committee won’t change the overall size or height of the building,” said Lynne Braddock Zollner, the city’s historic resources administrator.

The project will be the third multi-story building planned for the intersection in the last two years. The height of a proposed multi-story hotel/retail building on the southeast corner of the intersection sparked controversy in the East Lawrence neighborhood.

The Historic Resources Commission twice rejected plans for the multistory hotel, before city commissioners gave the project the approval it needed to proceed.

Fleming said this latest project fared better with the Historic Resources Commission because the proposed apartment building is farther from a residential neighborhood.

Now, city commissioners will wait to hear how the public reacts to plans for a roundabout at Ninth and New Hampshire streets. Fleming said the development group thinks a roundabout will improve pedestrian safety at the intersection.

“It will create some pedestrian islands there,” Fleming said. “It will narrow the distance you have to cross all at once.”

The idea also has a unique tie to Lawrence history, Fleming said. From 1910 to 1929, the Roosevelt Fountain that currently is in South Park was in the middle of the Ninth and New Hampshire intersection.

Fleming said the development group is not proposing to move the Roosevelt Fountain, but it would like to place a piece of public art in the center of the roundabout.

A date for city commissioners to hear the roundabout issue has not been set. The city also will have to hear a request to demolish the existing office building at the Ninth and New Hampshire site. The building has been occupied by Black Hills Energy and other users. Black Hills recently completed a deal with Compton to purchase First Management’s former headquarters building on North Iowa Street.

The plans approved by the Historic Resources Commission call for a building that will be seven stories tall, and will have apartments on floors two through seven. The ground floor will have space for a bank and a drive-thru lane, an apartment clubhouse and about 5,000 square feet of office space.

The building will include 121 apartments, with a mix of one, two and three-bedroom units. The 177,000 square foot building easily could add 200 or more residents to downtown Lawrence, Fleming said.

“We’ve seen some numbers that suggest every person who lives downtown spends $8,000 to $10,000 a year on goods or services downtown,” Fleming said. “If that is true, think about what that can do for downtown.”