Red Tape & Visas
Visa is a identity of people so if any non visa citizen who stay longer than three months are officially supposed to apply for a residence permit for which you'll have to show proof of among other things a regular income or sufficient funds to support yourself during your stay. EU passports are rarely stamped, however, so there is no evidence of how long you've been in the country. If your passport does get stamped, you can cross the border to Belgium or Germany.