Billionaire David Koch and wife Julia broke ground on a cutting-edge outpatient center at New York–Presbyterian Thursday — after making the biggest philanthropic gift in the hospital’s history.

The David H. Koch Center will offer innovative ambulatory care to patients being treated for cancer, digestive diseases and other conditions when it opens on York Avenue between East 68th and East 69th streets in 2018.

Koch donated $100 million to fund the center.

A hospital spokeswoman didn’t respond to a request for information about the project’s total cost.