The shine on the Helmsley Building has grown so bright lately it’s caught the attention of the country’s largest real estate company.

Indiana-based Simon Property Group, which owns 263 million square feet of leasable space around the world (mostly via malls), will move its New York headquarters to 11,652 square feet on the 22nd floor of 230 Park Avenue.

That brings the space leased in the building so far this year to 200,000 square feet, Brian Robin, of landlord Monday Properties, told The Commercial Observer. “The building always leases well” when the market is strong, he said. And strong the Manhattan office seems, with new leasing activity up 65.8 percent for the first nine months of this year, according to a recent CB Richard Ellis report.

“We’re doing a good job of communicating to the market and offering fair pricing,” Mr. Robin said. The deal is for 10 years and asking rents in the tower portion of the building are in the mid-$60s, Mr. Robin said.

Other tenants that have signed in 230 Park in the last year include a well-heeled mixed bag: Six Flags, Stanley Tools, Encyclopædia Britannica and law firms Satterlee Stephens Burke & Burke LLP and Lathrop & Gage. About 90 percent of the space leased this year has been renewals. “It’s pretty clear that once tenants come here, they find a reason to stay,” Mr. Robin said.

Of course, it can’t hurt that the iconic tower recently became the first landmarked building in the city to achieve LEED Gold Status, adding a trendy splash of green to some classic gold.

Laurence Briody and Anthony LoPresti of CB Richard Ellis represented the tenant. Paul Amrich, also of CBRE, and Monday Properties' Jordan Berger represented the landlord.

lkusisto@observer.com