The digital city maps of many small to medium-sized cities in Europe are on closer inspection inaccurate or incomplete. This is due not only to inadequate, rudimentary mapping, but also to the rapid change in the stock situation, as is the case, for example, with reconstruction work following natural catastrophes. Another problem is the failure of automated procedures in unusual situations, such as temporary facilities (for example scaffolding) in the area to be mapped. The result is that basic information such as street profiles, floor plans of buildings, addresses, points of interest are misrepresented or simply do not exist. This circumstance is a not inconsiderable disadvantage for the residents and visitors of a city and must be remedied. Instead of a classic survey, the attempt was made to map the old town of a medium-sized city by a combination of VGI, aerial photographs and existing, old plans. This reduces high survey costs and the associated time expenditure. The high rate of change and the presence of extraordinary situations was addressed by VGI "directly" and a timely mapping as up-to-date as possible was possible. The test area for the practical implementation was the old town of L'Aquila / Italy. On the basis of the findings gained in practice, a set of rules based on historical measurement instructions for the VGI mapping of small to medium-sized cities based on OpenStreetMap was set up. This gives the communities and interested OpenStreetMap cartographers guidance and thus the opportunity for independent, efficient, high-quality and cost-effective mapping.