AUBURN — Construction is underway at 186 Main St. for 18 market rate apartments and two commercial spaces — one designated for a restaurant or brewpub and the other likely a small office or retail space.

Jon Smith, president of developer Great Falls Construction, said foundation work got underway in the past week.

It’s a challenging project because the site is 0.16 acre and on a steep incline leading to Main Street. A large retaining wall will have to be removed to excavate the site, which will have access from Main Street and the lower level parking lot next to the Androscoggin River.

The 18 units will be a combination of seven two-bedroom, seven one-bedroom and four studio apartments. Twelve will front the river — four from each category according to Smith. Apartments will have a Juliet balcony, which offers an enhanced view but no platform or deck to stand on.

The ground floor and basement will be commercial space for a 5,000-square-foot restaurant and a smaller space for retail or other business. Smith is looking for tenants for both spaces. Mason’s Brewing Co. was originally making plans to lease the restaurant space but decided to open a location in Machias earlier this year.

“We do feel we’ll find the right person for that space,” Smith said Tuesday, referring to the 5,000-square-foot space, which is the entire ground floor, with elevator access from the Main Street entrance and from the river side of the building.

The commercial space on Main Street is just over 1,200 square feet, which Smith said would be good for a coffee shop, bakery, cafe, professional office, salon/barbershop or retail space.

Residents will have direct access to the Riverwalk from the back door of the building. Parking will be on-street and in the Mechanics Row parking garage.

Construction is expected to take between 12 and 14 months. Pricing for the apartments has not been announced.