Even with monumental inscriptions, you'd need to carefully filter them to make sure you only read old ones. The newer ones frequently include U, e.g. I like this little poem in a park in Coimbra: http://bloguinho.casa/img/2017/01/nemus-litterae-old.jpg (the park also includes more poems, which is pretty cool). Too bad we don't have such Latin poems in Porto, where I live now.