Major indoor attractions — museums, galleries, and landmark monuments such as the Colosseum or the Vatican — generally don't allow pets, with the common exception of very small pets carried in a bag, and always excepting certified service animals. This is genuinely changing in places: a growing number of open-air museums, markets, and piazza-based attractions welcome leashed pets, though this is still the exception rather than the rule and rules vary site by site.
Which outdoor attractions in Italy welcome dogs?
Outdoor attractions in general tell a much more welcoming story: piazzas, public gardens, and historic town centres are almost universally fine for a leashed dog.

