The castle on the northern edge of the village, built in the first half of the 14th century and extended in the 17th century, has been the seat of the von Plettenberg-Lenhausen family since the 15th century, which produced important personalities (visit only possible from the outside).
In addition to several historic courtyard houses, a Pietà created by the sculptor Wilhelm Achtermann (1799-1884) is worth seeing in the Marienkapelle, which was built especially for it.
Lenhausen was the seat of a Jewish synagogue community founded around 1760, probably one of the oldest in Westfalen. It existed here until around 1900 and included the entire district of Olpe and in the Hochsauerlandkreis Eslohe and Schmallenberg. The former cemetery and the "Stolpersteine" in front of the house of the last Jewish family living in Lenhausen still remind of the Jewish community.