Nagahama Castle (長浜城) stands on a low promontory at the southern edge of the castle park, its white walls reflected in the waters of Lake Biwa. The current structure is a 1983 reconstruction built over the original 1574 foundations — reinforced concrete inside, traditional castle silhouette outside. It houses a local history museum spread across five floors, with exhibits covering the castle's origins, the Azuchi-Momoyama period, and Nagahama's role in the civil wars of the sixteenth century.
The top floor is the real draw: on a clear day you can see across the full breadth of Biwa-ko to the Hira Mountains rising on the far shore. Early morning is best, before haze settles over the water. The castle park surrounding the base is pleasant to walk at any hour and includes a small beach area at the lake's edge.