Thursday night, street closures are in place and there's a new plan for protecting the grounds during the three-day event.
Stages are up, sound checks are underway, portable ATMs are ready for your withdrawals and music fans are on a mission.
"The bands, great atmosphere, new city, I've never been here before," said New Yorker Keith Foley. "New city brings us here."
With its cornucopia of musical acts, over 130, from the Red Hot Chilli Peppers to White Rabbits to Black Sabbath, Lollapalooza will draw over 300,000 people for its three-day run. That's 30,000 more than last year.
Speaking of last year, when there was more than a bit of gate crashing, this year will feature new, higher fencing, the type of fencing used during the NATO Summit, which are not easily moved or hopped.
"And all the sensitive landscaping is fenced off - some is double fenced," said Bob O'Neill of the Grant Park Conservancy.
That was one of last year's headaches. Some of Grant Park's gardens were smothered by many feet, but this year they're protected.
Heavy rains during last year's fest had the concert grounds become of giant mud-wrestling pits that required the promoter to pay $1 million for new sod. The forecast is for this year to be different.
"The only impact is on the turf," O'Neill said. "What's going to happen because it's not wet, it will get worn down but it won't get killed. Last year, it was like rot-tilling under people's feet. It just kills the grass."
The economic translation is that Lollapalooza translates into a $100 million boost to the economy. Eighty percent of the concertgoers are from out-of-state, 10 percent of them are from other countries, which is music to the ears of the man who founded this event
"Music is international discourse, you don't need to know the language, but you can feel the sentiment of the musicians so I guess that's why," said Lollapalooza founder Perry Farrell.
In addition to the tourist dollars, Lollapalooza is paying more in amusement taxes, which is welcomed by a city hungry for more revenue.