Ben Ashkenazy bought his first piece of property when he was right out of high school, with a little help from his dad. Three decades later, his collection boasts some of America’s best-known buildings.

As far as real estate tycoons go, though, he’s a candidate for least known.

He keeps a very low profile for someone whose company has a $12 billion portfolio --including Boston’s Faneuil Hall Marketplace, Washington’s Union Station and a piece of the Plaza Hotel in New York -- and just paid about $750 million for the Grosvenor House hotel on London’s Park Lane. Ashkenazy Acquisition Corp. itself had to scale a name-recognition hurdle to make an earlier deal in the British capital.

“The first time I took their call, I told them I didn’t know who they were and put the phone down,” said Robin Coady, whose firm Coady Supple negotiated the 2013 deal for the owner when Ashkenazy bought Old Spitalfields Market, which it has since sold. “I’d never heard of them.”

By then Ashkenazy Acquisition had built an empire of retail, hotel and office assets. And its 48-year-old founder and chairman was amassing a fortune, one that made it possible for him to hire the rapper Drake to perform for his daughter’s bat mitzvah at the Rainbow Room last year.