Dan Gilbert, billionaire founder of Quicken Loans and champion of downtown Detroit commercial real estate, last week announced he will buy the long-vacant 38-story Book Tower skyscraper and two other adjacent buildings on Washington Boulevard.

The latest in a series of acquisitions for Gilbert sizable portfolio under Bedrock Real Estate Services, the buildings will cost about $30 million total, to be paid to Vancouver-based AKNO Properties. That’s for the 1926 Book Tower, the 13-story Book Building and an adjacent 2-story community center.

Read our Q+A with Gilbert’s real estate partner Jim Ketai here.

The Detroit Free Press quoted Gilbert as saying he’s planning “a game-changing, mixed-use development.” The tower and the Book Building have been vacant since 2009, and renovations are expected to cost more than $100 million.