A huge chunk of real estate near the northern stretch of Nicollet Mall has been sold to a San Francisco firm for $100 million, according to a source with knowledge of the deal who prefers to remain anonymous.

The properties, loosely known as Washington Square, include 20 Washington Square, 100 Washington Square, 111 Washington Av. S. and a parking ramp at 25 First St. N. They span about 1 million square feet of office space.

The distinctive mid-century 20 Washington Square building is currently leased to Voya Financial, formerly ING.

The buyer is Shorenstein Properties, a San Francisco-based real estate investment trust. In late 2012, Shorenstein bought the City Center complex, which includes the former International Multifoods Tower, a 50-story building occupies a city block bordered by Nicollet Mall, Hennepin Avenue and 6th and 7th Streets. That deal's pricetag was about $206 million.