BOSTON — The historic Faneuil Hall Marketplace attracts an estimated 20 million visitors annually, making it one of the country’s most popular tourist attractions. But in recent years, the dozens of shops, pushcarts and restaurants that fill three separate buildings have drawn fewer and fewer Bostonians.

In fact, the city’s longest-serving mayor, the late Thomas M. Menino, used to say that the market was the only place in the city he could have lunch without being recognized, said Howard F. Elkus, a founding principal of Elkus Manfredi Architects, a Boston firm.

Hoping to lure the locals back, the marketplace’s operator, Ashkenazy Acquisition Corporation, a privately held real estate investment firm in New York, has proposed the first major overhaul of the property since the 1970s. Ashkenazy bought the ground lease to the city-owned marketplace in 2011, and has spent the last two years working with Mr. Elkus to develop a master plan.

The design team took its time collecting lots of local input and gaining a full understanding of the marketplace’s historical value, said Barry Lustig, Ashkenazy’s executive vice president.