The 16th-century Torre del Martello was where Napoleon was 'imprisoned' at the start of his fleeting exile on Elba in 1814 and the russet-red, hexagonal tower remained a prison until 1877. It and the archaeological ruins next door (part of a luxurious Roman villa known as 'La Linguella' built between the 1st and 5th centuries AD) are now part of this museum. Also of interest are terracotta friezes from the Villa de Romana delle Grotte in the main museum building.
In summer, an outdoor cinema is held in the internal courtyard here.