There are several shrines in Venice with inscriptions indicating that the shrines commemorate "Anno Mariano" (a "Marian year" dedicated to Mary).
The first of these years was 1954, declared by Pope Pius XII. An article published in 1953 explains it and says that the Pope asked for people all over the world to visit shrines to Mary during this year. He also wrote a special prayer for her.
I learned via google that hundreds of roadside shrines were built in Ireland during the Anno Mariano 1954.
I'm not sure that all of these Venetian shrines were built in 1954; my guess is that some of them were existing shrines that were renovated to commemorate Anno Mariano. This first one is on Giudecca and has a metal plaque at the bottom that says "Anno Mariano 1954."
A Cannaregio shrine that in addition to "Anno Mariano 1954" says "Regina della Pace, Prega per noi. La Parrocchia di San Giobbe."
Another Cannaregio shrine, this one a little worse for wear, with the same inscripition as the one above indicating that the shrine was built or is maintained by the Parish of San Giobbe.
This one is in Dorsoduro~
Another gorgeous Giudecca shrine, the inscription below this one says "Ricordo Anno Mariano 1954" (in memory of...).
This beautiful shrine on Murano with the Madonna Nikopeia inside has a stone plaque below that says "Anno Mariano 1954."
The second Marian Year was in 1987, decreed by Pope John Paul II. He also wrote a prayer for the Marian year. This Cannaregio shrine honors both of the Marian years. This is the only one I've found that mentions the second year.