The Palazzi Barbaro (plural) is made up of two adjacent buildings. The one on the left was built in 1425, Gothic in style, and is the one owned (in part) by the Curtis family.
The one on the right is more Baroque (possibly 16th or 17th century).
In 1881 Daniel and Ariana Curtis rented the upper story apartments of which they eventually bought in 1885. Their son, Raph Curtis studied painting with Sargent in Paris. Sargent's father was a cousin of Daniel Curtis. During their stay, the Curties' would receive visitors -- many expatriate Americans with Harvard or Boston connections such as Isabella Stewart Gardner, Vernon Lee, Henry James (who would model the Barbaro for his charater Milly Theale's palazzo in his book The Wings of the Dove),and John Singer Sargent (who painted the Curtises' in the opulent Ballroom).