The owner of the Riley Towers apartment complex is preparing to develop a 54-unit extension of the landmark downtown property.

The five-story building would be built at 225 E. North St., immediately west of Riley Towers’ south tower. The development site is owned by Barrett & Stokely Inc., which bought Riley Towers in 1993. A portion of the site is the former Hudson Street, which the city vacated last year at Barrett & Stokely’s request, and a surface parking lot that the company bought late last year from Regions Bank.

The proposal calls for 4,100 square feet of street-level retail along North Street. The balance of the first floor and the second floor would house 79 parking spaces. The third through fifth floors would house a mix of one- and two-bedroom apartments, with balconies.

The timing of the project could depend on whether the developer seeks rezoning of a portion of the site. In its current configuration, part of the project would be built on land tagged with an obsolete zoning classification that predates the 1970 merging of city and county governments. That part of the site must be rezoned, said Jeff York, a senior planner with the city’s Department of Metropolitan Development, or the project must be reconfigured to build around it.

The project is up for approval at a Jan. 28 meeting of the city’s Regional Center Hearing Examiner, but the developer is likely to seek a continuance because of the zoning issue.

Bryan Barrett, director of acquisitions for Barrett & Stokely, said his company is consulting with the project architect, Browning Day Mullins Dierdorf, to determine if the design can be downsized to avoid the land that must be rezoned. Barrett said chances are good his company will stick with the original design and seek the rezoning, which would add a couple of months to the approval process.

It’s not clear when the project would start. Barrett said his company wants to use the site this year as a staging area to refurbish the Riley Towers garage on the opposite side of North Street. Work on the new apartment building wouldn’t start until the garage work is finished and financing is secured, Barrett said.

He said there isn’t a firm price tag assigned to the project yet and the process of finding down financing hasn’t begun.

Riley Towers, a 525-unit complex comprising two 30-story towers and a 16-story building, is about 90 percent occupied, said Barrett, who noted his company rarely engages in the development of new apartments because of the expense. He said building adjacent to Riley will be more cost effective because the new apartment units can share Riley’s leasing office and tenant amenities, such as a clubhouse and swimming pool.

Riley Towers was built in 1963 and boasts the tallest residential buildings in the state. Original plans called for 10 of the 30-story towers.

The new building would be directly across the street from a portion of the Indianapolis Cultural Trail, a bike and pedestrian path being built throughout the downtown area. The North Street section of the trail is under construction.

William French, a retail real estate broker for Colliers Turley Martin Tucker, thinks the addition of the trail will create demand for retail space along that stretch of North Street. French represents the owner of two buildings and a parking lot at the northeast corner of Delaware and North, adjacent to the trail and across the street from the proposed Barrett & Stokely project.

“Once the cultural trail is completed, we’ll see that corner redeveloped eventually,” French said.