When I've asked my Czech friends what a "Mestsky Urad," is, they've told me there's no such thing, but as you can see here, they're simply wrong. "Uřad" means "office" in Czech, but it means more specifically a government office or authority, such as a Financni Urad (finance or tax office), Zivnostinsky Urad (business office), Kadastralni Urad (Cadastral Office), and so on. Having visited more than one Mestsky Urad, my understanding is that these buildings are meant as support buildings to the city hall, or radnice, where additional offices can be located, including those mentioned above.