Marketing giant Interpublic Group is moving to Century City and leasing a huge chunk of space that has been vacant since Northrop Grumman Corp. moved its corporate headquarters to Virginia.

IPG, a New York holding company, signed an 11-year deal for 150,000 square feet at 1840 Century Park East and an adjacent tower, according to brokerage Newmark Grubb Knight Frank, which represented IPG. About 700 employees are relocating.

Newmark called the deal the biggest relocation into Century City since 2004, when Creative Artists Agency announced its move to 2000 Avenue of the Stars, a new office building.

IPG and Newmark declined to disclose the value of the lease, but a real estate expert pegged it at more than $70 million.

Richard Haray, IPG’s senior vice president of corporate services, said Century City is more centrally located for IPG’s employees and major clients than its current location at West Hollywood’s Pacific Design Center. The new offices also are being redeveloped into “creative” offices with more shared work spaces.

IPG’s subsidiaries are expected to complete the move by the end of 2016, Haray said. They include public relations heavyweights PMK-BNC and Rogers & Cowan, which will have signage on top of one of the towers.

Steve Kolsky, who represented IPG in leasing, said the space has been vacant since Northrop completed its move two years ago.

The deal, he said, is the latest example that Century City, long known as a legal and financial center, is becoming more tied with entertainment.

“It’s a really big jolt to Century City,” he said.

andrew.khouri@latimes.com