The Ponte Gobbo, the background of the Mona Lisa
The Ponte Gobbo (also called Ponte Vecchio or Ponte del Diavolo) is an ancient bridge with an irregular profile, which crosses the Trebbia river in Bobbio in the province of Piacenza.
Photo of Bobbio by me 
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The Ponte Vecchio di Bobbio, 273 meters long, has been called Ponte Gobbo for the particular irregular profile with 11 unequal arches between them and placed at different heights.
Recent studies on the landscape (2015), conducted by the Piacenza Bellocchi studio, have validated, through a 3D reconstruction and other technical checks, the research by Carla Glori (published in 2011) which identifies the Mona Lisa in Bianca Giovanna Sforza against the background of Bobbio, she legitimate eldest daughter of Ludovico il Moro, wife of Galeazzo Sanseverino and Lady of Bobbio, Voghera and Castel San Giovanni; the results of the verification carried out support the hypothesis that the bridge painted by Leonardo (to the right of the observer and on the left of the famous Gioconda) coincides with the Ponte Gobbo di Bobbio, placing the point of view at a window on the north-east facade of the Malaspina-Dal Verme castle.
Thank you! :-)