La soffitta: Italian, directly translated to “the attic”

Hall of the Five Hundred: A large room in the Palazzo Vecchio filled with Renaissance paintings and other artifacts. It was built by Simone del Pollaiuolo and Francesco Domenico in 1494. It was formerly a room that housed the governing body of Florence.

The Hall of the Five Hundred http://en.comune.fi.it/images/salone_500.jpg

Nebbiolo: A red italian wine grape, used to make wine. Generally associated with Fog (like it is in Brown’s usage of the word) due to the onset of fog in the region that they are grown.

garret: A habitable attic

truss: An architectural concept involving a complex system of beams and the utilization of pressure points. Generally found in many Renaissance era ceiling supports

king post-and-strut: Another architectural concept that works hand in hand with the truss(es) to provide more support for the ceiling

Duke of Athens stairway: A somewhat obscured stairway within the Palazzo Vecchio that Langdon knows about. It was a significant part of his plan to escape the attic with Dr. Brooks.

St. Mark’s Square: The large, famous square in Venice, Italy in front of St. Mark’s Basilica.

St Mark’s Square, with the Basilica looming behind it. http://www.filmapia.com/sites/default/files/filmapia/pub/place/067-venice-st-marks-sq.jpg

Hotel Danieli: A very nice hotel in Venice. Very close to St. Marks Square.

The Apotheosis of Cosimo I: A painting of Cosimo de Medici I ascending to heaven. This painting is an inspiration for the Washington painting, described below. 

The Apotheosis of Washington: A painting of George Washington ascending to heaven on the inside roof of the Capitol Rotunda in Washington D.C. It plays a major role in the plot of The Lost Symbol, another Dan Brown book/Robert Langdon adventure that takes place in America’s Capital.

The Apotheosis of Washington http://upload.wikimedia.org/wikipedia/commons/6/69/Apotheosis_of_George_Washington.jpg