Tickets for day one at the festival in Grant Park have sold out, Lollapalooza spokeswoman Shelby Meade said on Thursday.

The city estimates that 75,000 people will come to see headliners Radiohead in concert, seven years after the group last performed in Hutchinson Field to a crowd of 25,000 people in 2001.

Those who are interested can still buy tickets for the price of $80 fro Saturday and Sunday. The box office is situated across from Grant Park on Columbus between Balbo and Congress and it is open from 10 a.m. to 10 p.m. Friday, Saturday and Sunday, the Chicago Sun-Times informs.

As hot weather was forecasted for the weekend, measures were taken to prevent any possible problems. Medical facilities, misting stations and cooling buses will be placed al across the park where the festival will take place.

The city is going to be better prepared this time, after serious problems happened at two other local events last year. The Chicago Marathon had to be shut down last fall mid-race, because organizers weren’t prepared for the heat. Also, one person was shut down at The Taste of Chicago last month.

This year at Lollapalooza, Superintendent Jody Weis, of Chicago police Dept., says plenty of officers will also be present.

"We'll be working closely with the Office of Emergency Management and Communications to monitor cameras so we'll have real time intelligence where we can deploy our resources to meet any challenges we might have," said Weis, according to ABC News.

The stages, the sound checking and the first rehearsal sounds, they all show the Grant Park is going to rock again.

During the three days, besides having fun in the sun, festival goers will enjoy good music of very different genres.

The lineup includes appearances by Radiohead, Rage Against the Machine, Kanye West, Wilco, and the Raconteurs, plus Gnarls Barkley, Cat Power, Broken Social Scene, The Go! Team, the Cool Kids, Kid Sister, the Black Keys, Mates of State, Nine Inch Nails and The Kills.

And let’s not forget about Lupe Fiasco, the National, Explosions in the Sky, Okkervil River, CSS, Spank Rock, Black Kids, Black Lips, Gogol Bordello, Amadou & Mariam, Rogue Wave, the Gutter Twins, Yeasayer, Dr. Dog, the Octopus Project, and Cadence Weapon.