Lincoln Park Zoo’s annual ZooLights display flips the switch Friday on its largest festival of holiday lighting ever.

Now in its 22nd year, ZooLights will be expanded to extend across the entire zoo for the first time.

Two million lights will be strung from Farm-in the-Zoo at the southern end to the new Arctic Tundra exhibit near Fullerton Avenue to the north, featuring the zoo’s new polar bear, Siku.

Hours are extended as well, 4:30-9 p.m. Friday, Saturday and Sunday and again next weekend, Dec. 2-4, then nightly Dec. 9 through Jan. 1 (except, of course, for Dec. 24 and 25).

The zoo is bringing back last year’s addition, Monday Family Nights on Dec. 12, 19 and 26.

On the other hand, the zoo offers a special Adults Night Out for visitors 18 and up on Dec. 7 from 6:30-10. That comes at a cost of $15, $12 for zoo members.

As always, admission is otherwise free, but there are some events that come at a cost.

Ice skating also returns at Farm-in-the-Zoo starting Friday, at a cost of $5. Skate rentals are an additional $5. Hours vary, so check the rink schedule.

The third annual BrewLights night featuring a dozen local craft, seasonal and import beers on tap throughout the zoo is set for Dec. 1, with tickets $49, $60 at the door. Visitors must be 21.

The zoo initiates a new Holiday Market Nov. 29. Entry is $10, $8 for members.

The Chris White Trio plays a tribute to Vince Guaraldi’s soundtrack to “A Charlie Brown Christmas” Dec. 15 at Cafe Brauer. Tickets start at $20.

And finally there’s a Members Only night at, of course, no additional cost for zoo members.