Greece is to deploy more than 14,000 police, coast guard and soldiers during the summit of European Union leaders that begins on Thursday.
Organisers in Thessaloniki are scared mass protests could turn violent.
Eager to keep the peace, they are offering demonstrators free bus services in the town, camping facilities in local parks, and venues to stage meetings and press conferences.
They have also set up roadblocks, sea blockades and an airspace cordon to stop anyone getting near the summit venue in nearby Porto Carras.