David L.
Google
The Museo Hendrik Christian Andersen Museum is certainly one of Rome's quirkier museums.
Between 1922 and 1925, the Norwegian-American sculptor Hendrik Christian Andersen designed and built Villa Hélène (named after his beloved mother, who lived with him until her death in 1927), a grand house-cum-studio, which, on his death, he bequeathed (full of his sculptures) to the Italian nation.
The Villa Hélène, which houses a motley collection of Andersen's sculptures, lies just outside the Porta del Popolo. It is well worth seeking out.