Just two months ago, Vegas shooter Stephen Paddock booked two hotel rooms at the Blackstone Hotel in Chicago during Lollapalooza. Both of these rooms were directly above Grant Park, which would house somewhere around 400,000 concert goers for four days.
Paddock booked one room on August 1st, the second room on August 3rd. Both rooms had a checkout date of August 6th, which was the last day of Lollapalooza. Paddock requested both rooms have a view of the park, overlooking the main stage as well as several other smaller stages.
According to TMZ, Paddock never showed up to the hotel. However, it does show that this massacre was probably in the planning stages for a long time.