The city's biggest tech employer is about to get even bigger.

Google has started construction work to revitalize Pier 57 at Hudson River Park.

Mayor Bill de Blasio visited Google's offices in Chelsea to get a preview of the project.

The $350 million rehab will include three acres of public green space and a rooftop park.

The mayor praised the company for creating more job opportunities in the tech sector.

"The beauty of this strategy is that it ends up giving us a genuine campus in the heart of New York," said Eric Schmidt, executive chairman of Alphabet, Inc.

"This is how we restore the middle class we once knew, through companies that have consitently good-paying jobs, with great benefits and great career paths ahead," de Blasio said.

The mayor says the goal is to open the new Pier 57 by the end of 2017.