Boston wants to sell the Lafayette Garage at 1 Avenue de Lafayette in downtown to help pay for a $500 million affordable housing initiative. Mayor Marty Walsh proposed the sale during his State of the City address on January 7. The city plans to issue a request for proposals in the spring.

It’s unlikely the 1,000-space underground garage will follow the path of the former Winthrop Square Garage, however. That site is due to host one of the tallest U.S. buildings north of New York City, whereas the Lafayette Garage does not include any of the air rights above it. Other properties own and occupy those.

The sale of Winthrop Square, however, does provide a clue as to how much Lafayette could command.

The dilapidated, four-story facility traded for $102 million in late 2018. The city put tens of millions of that toward affordable housing as well as toward park upgrades and other efforts. Developer Millennium Partners, which won the bidding for the garage in 2016, is building a 691-foot mixed-use tower on the site. It’s expected to open in 2022.

Walsh expects the sale of the Lafayette Garage to close an approximately $400 million gap in his $500 million affordable housing plan. The city is already prepared to commit $100 million in existing resources, he said.

“That alone doubles our current investment,” Walsh said during the State of the City. “We will generate the additional revenue by working with the City Council to sell the Lafayette Garage downtown and working with the state Legislature to approve the transfer tax we passed last month.”

That tax would add a surcharge of up to 2 percent on most property sales in Boston of at least $2 million.

If the Lafayette Garage sells, it will likely be months, maybe years, before the city sees any payoff. It was more than two years between the selection of Millennium Partners for the Winthrop Square project and the $102 million payout, which came after the sale closed.