The firm will retain the 4^th floor and expand into and 3^rd floor, sources familiar with the deal said.

Mark Weiss, a vice president at Newmark Grubb Knight Frank, represented the tenant with Robert Silver and Robert Eisenberg.  The brokers declined comment.

The Arch Atop 570 Lexington Avenue (Credit: nyc-architecture.com)

Fabiani Cohen & Hall LLP did not return multiple calls seeking comment.  The landlord, The Feil Organization, also did not return calls and emails seeking comment.

The 50-story, 450,622-square-foot art deco building features a signature tower with a crown of limestone Gothic spires and brickwork accented with filigree decoration and lightning bolt motifs.

When it was designed in 1931 (completed in 1932) by Cross and Cross, the property was known as the RCA Building, and the crown sought to depict the electricity of the now defunct Radio Corporation of America’s radio waves.