The Triangle — a retail, dining and entertainment center located where Newport Boulevard, Harbor Boulevard and 19th Street intersect in Costa Mesa — was sold recently to an undisclosed buyer for $55.7 million.

Terms of the deal were announced this week in a news release from CBRE, which brokered the purchase along with National Retail Partners — West.

That release identified the buyer only as “a Los Angeles-based family office syndicate.”

A representative from Irvine-based Greenlaw Partners, which has owned the complex since 2006, confirmed the sale in an email but did not offer any details as to the motivation behind it or the identity of the buyer.

Dubbed Triangle Square when it opened in 1992, the downtown center initially enjoyed some success but struggled in the early and mid-2000s as the recession struck and tenants departed.

After buying the center, Greenlaw rebranded it The Triangle and developed a master plan to remodel, renovate and revitalize the space by focusing more on dining and entertainment over retail.

The complex — which was nearly fully occupied at the time of the sale, according to the press release — now features a diverse mix of tenants including restaurants, 24 Hour Fitness, the Tavern + Bowl bowling alley, Time Nightclub and Starlight Triangle Square Cinemas movie theater.

A dueling-piano bar, Keys on Main, is slated to open early next year.

luke.money@latimes.com

Twitter @LukeMMoney