Over 6,551,046 Visitors in 2015 !!! An all time record!!!
Jan. 2015 - Culture Minister Dario Franceschini said that in 2015 Italy's museums and monuments had their "best ever" year, drawing a record 43 million visitors and generating 155 million euros of revenue. "It's the best result ever in our country's history, an all-time record for Italian museums " Franceschini said.
Visitors to Italian museums have increased by 4.5 million over the past two years and climbed 2.5 million over the last year alone, reversing a negative trend seen in other countries, Franceschini said.
The top attractions in 2015 included Rome's Colosseum (visited by over 6.5 million people, with a revenue of 44.613.000 Euro) and the ancient Roman city of Pompeii (2.9 million).
Actually, the most visited monument is the Pantheon in Rome (7.496.188 visitors in 2015) but there the entrance is free so it does not appear in the statistics of museums income.
The image below can be found here at the Ministry site