Petitioners have filed a lawsuit against the city to try to stop NYU from expanding into Greenwich Village.
11 groups, including some university faculty, want to block the $6 billion proposal, known as the Sexton Plan.
It includes four new buildings and below-ground construction near NYU's core campus around Washington Square Park.
The lawsuit alleges the city illegally gave away public land to the university.
NYU representatives have said the development will primarily be used for classrooms and faculty research space.
The City Council overwhelmingly approved the expansion plan 44-to-1 in July.
In response to the lawsuit, the city law department says it's confident the plan will be upheld.
NY1 reached out to NYU for comment on the suit and is waiting for a response.