ROCKLAND — A Portland development company has purchased the largest shopping center in Rockland.

Treadstone LLC acquired the Harbor Plaza Shopping Center on Sept. 30 from John Morris, Susan Morris, Samuel Morris, and Joshua Morris. The sale price, according to records filed with the Maine Bureau of Revenue Services, was $14 million.

The city has the property assessed at $12.8 million and the annual tax bill is $311,000. This does not include the personal property on equipment owned by the tenants.

Harbor Plaza is located at 235 Camden St. and includes the anchor tenants of Shaw’s Supermarket, T.J. Maxx, and Staples. The center also includes China Coast restaurant, Pet Quarters, H&R Block, Fed Cap Opportunity, the UPS Store, Label Center, and Rent-A-Center.

Josh Soley, manager of Treadstone, said the plan is to modernize the shopping center. He said he would like to attract more tenants to fill the center. If the roof load is sufficient, solar panels will be installed on the roof. Electric vehicle charging stations will be installed.

There are four empty retail spaces in the center.

John Morris of Waldoboro designed and developed the shopping center which was built in 1987. The original anchor tenants were Shaw’s and Zayre’s department store.

When the shopping center was approved by the Planning Board in June 1985, several neighbors on Waldo Avenue and Glen Street went to court to block the project, claiming it would harm the character of the then residential area and that added vehicle traffic would create a safety hazard for the neighborhood. The case went all the way to the Maine Supreme Judicial Court which rejected the neighbors appeal.