Keystone Property Group is seeking a new namesake tenant for its Center City office building that now bears Dow Chemical Co.'s nameplate.

The Conshohocken-based real estate investment firm has hired brokerage JLL to market space in the building, including a 200,000-square-foot continuous block. The lease could include naming rights for the Sixth and Market Streets property, JLL said in a release.

Much of the space up for lease is being vacated by Dow, which announced in July that it was relocating 350 employees at the building to Collegeville.

The 1964 structure is still known to many by the name of its original main tenant, Rohm & Haas Co., which was acquired by Dow in 2009.

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