Sculpture of Roman Emperor Claudius' head.

Inside the Museum of the Castle's Archaeological Crypt, at Convento de Aracoelli Street, Alcácer do Sal.
It was frequent to sculpt heads of important cityzens and insert them on top of headless anonymous statues. If another important cityzen came up, his head's sculpture would replace that of someone meanwhile outdated.
The Christmas cap must have been an idea of the museum's staff...