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> In the UK it's good enough to give someone a post-code and door number and you can get to their front door. How that would work globally I do not know

We do have post-codes in Romania but nobody ever uses them. But at least now I understand why one of my first bosses, who was from the UK, was insisting so much that me, the programmer, would implement a reverse geo-thingie that would associate a post-code to a specific physical address (this was back in 2006-2007, the golden days of web-mapping).

In theory there should be only one high street per locality. I didn't try the app with london urls (only berwick street which worked fine [1]). In theory if you can unambiguously write the address of a place without relying on the postcode, then you should be able to construct a unique url for the place.

1. http://nice-map-urls.herokuapp.com/united-kingdom/greater-lo...

Theory meets practise.

It is not possible to unambiguously write all addresses in the UK without including the post code.

The post code and door number are the primary key of the data.

Edit 1:

A fine example: http://nominatim.openstreetmap.org/search.php?q=high+road%2C... Zoom out one level and you'll see that High Road is surrounded on both sides by High Street. And yes, that is correct.... High Street > High Road > High Street = One road in one very old town.

Crazily if you look down a little further you'll see the Southern High Street (A408) goes East, and what is technically another High Street heads on Southwards.

3 High Streets, and 1 High Road... in less than 1 mile in 1 town.

I was actually looking for the Church Road in Uxbridge that comes off of Church Road, but I think Google Maps incorrectly has both of them as Church Lane.

Edit 2:

Here you go: http://nice-map-urls.herokuapp.com/ub5/united-kingdom/englan...

Church Lane coming off of Church Lane. One is the A312, the other is just Church Lane.

Google is wrong on this, they're both called Church Road. And historically they were the same thing, but as it evolved from a way to get to the church to a market thoroughfare one main road emerged and left the other road as a side road. Over time this actually led to both roads being distinct, and with their own door numbering schemes, even though they meet each other.

I find the history of places as fascinating as the history of languages.

The postcode and door number (or even street) is not enough in the uk unless you are in a town (and even then not always). Look up some rural postcodes, or blocks of flats with names rather than a number.

The town I grew up in had a Something St that at the top of the hill changed to a different street. A street also called Something St. Both have the same postcode. There are many duplicate house numbers.

I think they were originally separate unjoined streets. But a road was built up the hill, joining them together. I guess people couldn't agree on who should have their houses renumbered.

If manually specifying the address you probably have enough wiggle room to specify which 10 Something St you mean. I've encountered systems online that will try to normalize and correct street addresses to an official format... I could imagine that these would cause problems.

(And don't confuse those addresses with the 10 New Something St, or 10 Something Rd, both of which are only a few hundred meters away.)

In theory there should be only one high street per locality.

You will have to throw out assumptions like that as soon as you start dealing with addresses in any serious manner.

High Street is a name for the most important shopping street or main thoroughfare in UK convention. I've never been to a place that had 2 high streets and certainly not 2 called High Street. [Many towns in Scotland have a sort of quadrangle of main shopping streets it seems - one is often part cobbled and called Market Street]. If an area/town/village has multiple streets of equal worth then they might be termed North and South street or named for a building like Church Street or such.

In the past having name collisions would simply be a terrible convention, nowadays we have regulations that prevent it from happening with new names (same for housing).

The Scottish village I grew up in had a High Street - but it wasn't the High Street in the sense of "most important shopping street" (or indeed in any other sense). The "most important" street was Church Street - which even had a shop and a church, whereas High Street only had one church. :-)

High Streets can also be overtaken by events. Edinburgh's High Street hasn't been the most important street for anyone other than tourists for a few hundred years.

Use the Royal Mail's 'find an address' tool [1] to look up the following postcodes:

SE20 7QR, SE25 6EP, E13 0AP, E15 2LR, W5 5DB, W3 6LJ, NW10 4SJ, N14 6BW

For a map see [2]. As you can see, plenty there are several roads the Royal Mail considers to be called High Street, London!

[1] http://www.royalmail.com/postcode-finder [2] https://maps.google.co.uk/maps?q=from:SE20+7QR+to:SE25+6EP+t...

In theory there should be only one high street per locality.

There was a story on Russian news a few weeks ago how there are multiple streets with the same name in the city of Sochi. They are tackling the problem before the olympics arrive, but your assumption is probably violated elsewhere as well.

That's not uncommon. London postcodes were invented because there were numerous streets with the same name in London.

That's not true.

London post codes are the result of London moving from a single post town to a town with multiple towns (for the purpose of postal sorting offices).

The whole concept of a central post office broke down in the 1850s and London needed to be sub-divided to solve that.

Postal codes merely solved the routing problem between divisions, and wasn't a response to the street names problem.

http://en.wikipedia.org/wiki/London_postal_district

One of the little known "Did you know" is that the primary numbers of postal areas in London were originally alphabetically sorted (which largely remains the case today unless that postal area has been extended or further sub-divided).

How that would work globally I do not know... fine for most of the Western World, useless in India maybe, etc.

Forget India, Ireland (right beside the UK) has no postcodes.

Even within the UK (Fermanagh) postcode usage can be spotty.

The thing with India is that roads didn't necessarily have names or numbers.

I navigated more by "When you're past the ornately carved and colourful chapel go straight on and do a right, turn left when you see the blue building, we're in the red one third down with the blue door.".

Some places have such details, but a lot of the towns and villages just added roads organically and wouldn't stop to centrally register them, name them, number them, assign them identifiers, etc.