The Bronx Zoo flipped the switch on for its "Holiday Lights" display Tuesday night.

Families walked the grounds, took pictures and even roasted marshmallows on the preview night before it officially opens to the public on Nov. 21.

Millions of lights and hundreds of illuminated animals are now sprawled across the Bronx landmark for the holiday season.

"It allows us to invite people to the zoo in a different context," shares Bronx Zoo director Jim Breheny on his love of the event. "The best thing that happens during Holiday Lights is if it snows!"

This year, the display includes a new "Freeze Zone," which features a snow slide, a virtual snow ball toss and photo-op's with snowmen.

The lights will be on display from Nov. 21 through Jan. 4 on select nights.

Click here to see the schedule and buy tickets.