The Ruined Tower

Painted in 1838 by the American artist, Thomas Cole, Italian Coast Scene with Ruined Tower, was generally not known to the public until purchased by the National Gallery of Art from a private collector in 1993.
 

The tower is similar to those THC has seen along the Amalfi Coast and commonly known as Saracen Towers, originally built in the 9th and 10th centuries to provide early warning of Saracen pirates coming from Sicily and North Africa.  To see what one of these towers looks like today go here and here.