I've taken the liberty of stealing another photo from PaNiC rOmE for no other reason than that I liked it.
It shows the via Giulia in the rione Regola. It runs parallel to the Lungotevere from Ponte Sisto until largo dei Fiorentini. It was designed by Bramante for Pope Julius II and was the first Renaissance street to cut throught the tangled alleys of the old centre.I remember when I first went to Italy (and I was a very bad traveller), the numbering of buildings along a street was one of the many little things that brought on severe existential doubts and made me question my fitness for Life on Earth. For instance, I didn't understand that residential and non-residential buildings were given two completely separate sequences so that I didn't need to suffer because of the fact that with one step I went from number 24 to number 2. It was normal. As I have always suspected, it was my own fault that I suffered.
The street numbering is strange. For one thing, it jumps by ones, twos and tens (because of the demolition of various buildings through the ages). For another, the odds and evens are mixed up. But most original of all, on one side they rise while on the other they fall.