The biggest store in the world is about to get even bigger.

Macy's says it is planning to spend roughly $400 million over the next four years to renovate and expand its flagship store in Midtown Manhattan's Herald Square.

About 100,000 square feet of selling space will be added and every floor will be affected.

As part of the renovations, Macy's will create the world's largest women's shoe department and add about 800 jobs by fall 2015, when renovations are scheduled to be completed

The large-scale makeover begins next spring.