Philadelphia had lots of problems with anarchists during the last Republican Convention there. Several Pennsyvania State Troopers that I knew were detailed there to beef up security. Things got pretty dicey on the streets.
Philadelphia with it’s narrow alleys in between the main arteries is tailor made for trouble.
Cleveland is a slightly different deal. The IX center is located at the airport, so it is locked down on three sides by airport, with one road access. The issue will be with convention goers staying downtown.