City rights are a feature of the medieval history of the Low Countries, and, more generally, the Holy Roman Empire of the German Nation. A liege lord, usually a count, duke or similar member of the high nobility, granted to a town or village he owned certain town privileges that places without city rights did not have.
In Belgium, Luxembourg, and the Netherlands, a town, often proudly, calls itself a city if it obtained a complete package of city rights at some point in its history. Its current population is not relevant, so there are some very small cities. The smallest is Staverden in the Netherlands, with 40 inhabitants. In Belgium, Durbuy is the smallest city, whilst the smallest in Luxembourg is Vianden.