The 1760 Market St. office tower in Center City has been acquired by Philadelphia-based attorney and property investor Victor F. Keen.

Keen paid $31.5 million for the 14-story, 126,689-square-foot office building, a spokesman for law firm Duane Morris LLP, with which Keen is affiliated, said in an email Wednesday.

Keen bought the property from a joint venture between Alterra Property Group and Stockton Real Estate Advisors. The Philadelphia-based firms had made improvements to the property's lobby and other common areas amid other upgrades after acquiring it in 2015 for $20.15 million, according to CoStar Group, a market tracker.

Alterra and Stockton were represented in the sale to Keen by brokers James Galbally and Brett Grifo of commercial real estate firm JLL, that company said in a separate release.

The purchase is the largest Philadelphia acquisition to date for Keen, who is active in New York's real estate markets, the Duane Morris spokesman said.