May a municipality enforce a municipal ordinance outside its corporate boundaries (e.g., on land the municipality owns that is located in an adjacent town)?
No. The general rule is that absent an express grant of authority to enforce an ordinance extraterritorially, municipal ordinances have no effect outside of the municipality's corporate boundaries. See Wisconsin's Environmental Decade, Inc. v. DNR, 85 Wis.2d 518, 271 N.W.2d 69, 76 n. 8 (1978).
Municipal ordinances would apply to territory owned by and lying near but not necessarily contiguous to a city or village if annexed under Wis. Stat. sec 66.0223.