Gulyay-gorod, also guliai-gorod, gulay-gorod (Russian: гуляй-город, Гуляй-городок, literally: "wandering town"), was a mobile fortification used by the Russian army in the 16th and 17th centuries. A gulyay-gorod was made of wooden walls with holes for guns installed on wheels or sleds. The gulyay-gorod was designed as a fortification in steppes, whose flat, void landscape provided no natural shelter.