In Rome, many houses have large numbers. For example, 3187 as on photo. It is obviously not the post address of the house but something else.

Roman Number

What do they mean? Is it a number in some catalogue?

  • 1
    Do you remember the road name?
    – motoDrizzt
    Jun 12, 2017 at 9:11
  • @JoeErNano: I have some suspects that you know the answer quite well ;-)
    – motoDrizzt
    Jun 12, 2017 at 9:15
  • 1
    @motoDrizzt This one is on Piazza di Santa Maria in Trastevere. But I've seen such large numbers also in other city districts. Following the link you will look right at this corner - goo.gl/maps/Wf8ZvGZHKXD2
    – Neusser
    Jun 12, 2017 at 9:18
  • 1
    A similar system is still used in Prague - every house has a street number and a district number. The street number designates the sequence of the house within a particular street, while the district number is a unique identifier of that house within the entire subdivision of the city and is completely independent of the street.
    – JonathanReez
    Jun 12, 2017 at 11:02
  • 1
    I've no idea what the exact answer is, but old houses may have historical signs that have "protected" status and can't be removed. For example in my village in the UK, there are old several houses with numbered plates relating to their former owners being members of a private fire insurance scheme - nothing to do with postal addresses at all.
    – alephzero
    Jun 13, 2017 at 0:59

1 Answer 1


Those are plates that in the 19th century identified individual gaslights, which were installed in Rome from 1854, starting with 44 streetlamps, and then proceeding to install thousands of them. On the nearest building wall the corresponding number on a maiolica plate was affixed, to uniquely identify that particular streetlamp.

Later the gaslights were progressively substituted with electrical ones, possibly in a different location, but the numbers remained.

The story is told in a blog devoted to Rome (in Italian).

  • 2
    I stand corrected. Well done for tracking this down! I spent hours looking for this and even asked in a few places in Trastevere where they had these numbers on the building and they didn't know what they were! Ah, I see that the blog page was put up this month.
    – Berwyn
    Jul 18, 2017 at 11:31

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