The city's biggest music festival – Lollapalooza - kicks off Thursday, bringing music, crowds and the potential for trouble.
On Lolla eve, the bands and the fans are getting ready. But so are police and emergency rooms.
With the music and the crowds also comes a huge security effort during the sold-out festival, so expect bag searches and pat downs.
Plus, there's a long list of items you can't bring in, including e-cigarettes or vaping devices, spray sunscreen or other aerosols, umbrellas, skateboards, scooters or bikes, and outside food or drink, except two sealed water bottles.
After 13 years, Chicago’s safety plan has set the standard for Lolla's in six other countries.
“We don't take any of that for granted,” said OEMC First Deputy Rich Guidice. “Just yesterday we had a public safety meeting and went through a bunch of different scenarios on events taking place across the world and how we would respond to all that taking place.”
For example, they studied the recent suicide bombing at an Ariana Grande concert in Manchester England.
“Lately with everything in the news and stuff, it's becoming more prevalent and scary of what could happen but I just hope for the best. And hope that everyone is just here to have fun and listen to music,” said Lolla-goer Daniela Cerdas.
Acts like Chance the Rapper will draw 100 thousand people each day of the four day festival, and mixed in the giant crowd will be intoxicated teens.
Lurie Children's Hospital says Lollapalooza weekend is the worst in the city for underage drinking, and a couple 19 year old's don't find that at all surprising.
“I'm sure we'll see girls passed out or throwing up, but that's common at any festival really,” said Rachel Iliovici.
“You just have to be careful and stick with your friends and make sure we don't get separated,” said Victoria Dudek.