Lomnice nad Popelkou is a town situated in the Semily District within the Liberec Region of the Czech Republic. It lies on the border between the Giant Mountains Foothills and the Ještěd–Kozákov Ridge, positioned along the Popelka Stream. The Cidlina River originates in the southern part of its municipal territory, while the highest point is the mountain Tábor at 678 meters above sea level.