A nearly 7,000-square-foot penthouse at the Residences at Two Liberty Place has sold for almost $11 million, a sale that could be the largest yet at the luxury condominium tower.

The Philadelphia Business Journal reported the sale Tuesday. Representatives from iStar Financial Inc., the owner of the property, and Dranoff Properties, which marketed and sold the units, declined comment.

The sale of the unit, located on the 57th floor of the tower, comes more than a year and a half after the high-end condos were put on the market. The buyer was not disclosed.

At 16th and Chestnut Streets, Two Liberty Place has been a mainstay in the Philadelphia skyline since it was built and completed in 1990 as a primarily commercial building. In 2005, residences were carved from floors 42 through 57 by American Capital Partners and the Falcone Group.

In 2012, iStar Financial took title to the unsold space, and then partnered with Dranoff Properties to market and sell the units.