Nürnberg has been chosen by the neo-Nazi NPD party as the site for their central demonstration, sparking the deployment of at least 3,000 policemen, and an expected 10,000 protestors, including a number of mainstream politicians.
The march has been given permission for a route which the German Jewish Council said goes past a Jewish old people's home and the town's Jewish cultural centre.
But the decision was defended by Nürnberg's Jewish cultural association, which said it had carefully agreed the route with the city and it was far enough away from Jewish establishments.
Hamburg is more likely to turn violent, with a strong left-wing scene determined to give the far-right demonstrators a hard time. They are expected to be joined by many protestors from Berlin, which is just a couple of hours' drive away.
The NPD and other extremists have registered their march to go through Barmbek, a traditionally left-wing, working class area. The scene's left-wingers are expected to be joined by a mix of trade unionists, politicians and church-goers in their protest.
Wednesday night, often a time for fights with the police in many of Germany's larger cities in the run up to May 1, was largely peaceful in Berlin, but several people were arrested in central Hamburg.
A barricade was set alight in the Schanzenviertel of the city, and a stand-off between a number of punks and policemen ended with a handful of arrests.