Teotihuacan

near San Martín de las PirámidesState of MexicoMexico

With a code: #GD349-DH7J0
Said aloud: Teotihuacan DH7J0

What the code says

The Grid Point Code for Teotihuacan is #GD349-DH7J0. It names a cell 2.56 m north to south and 3.22 m east to west, centred on 19°41'33.03"N, 98°50'38.00"W, and it turns back into that cell on any phone or computer by arithmetic alone: no network, no account, no lookup table.

What it is: Ancient Mesoamerican city
Code: #GD349-DH7J0
With a check character: #GD349-DH7J0*X
Short form: DH7J0
Cell centre: 19.692507, -98.843889
Cell size: 2.56 m by 3.22 m
Region: State of Mexico
Country: Mexico

How to give this address

On a sign, a form or a delivery note: The whole code, #GD349-DH7J0. It needs nothing else: no city, no street, no network to read it back.
Said aloud, in State of Mexico: Teotihuacan DH7J0: a name both people know, then the last five characters. They give back the exact code for anywhere within 4.0 km north or south and 5.0 km east or west of Teotihuacan. Further away the same five name somewhere else, which is why the whole code is what goes on a sign.
Copied by hand, or read over a phone: #GD349-DH7J0*X. The character on the end catches any single mistyped symbol and any two neighbours swapped.
As a link or a square code: Open it on the map, move to the exact door, and add directions if the code needs help: "blue gate, second floor". The link and the square code carry them. Nothing is kept on this site.

From the city to the door

The first four characters name a cell about 40 km by 50.3 km here. Each one after that picks one of 25 inside the last, so the whole ten name a spot about the size of a doorway.

GD34Metropolitan area40 km by 50.3 km
GD349District8 km by 10.1 km
GD349DSuburb1.6 km by 2.01 km
GD349DHA few streets320 m by 402 m
GD349DH7Building64 m by 80.5 m
GD349DH7JEntrance12.8 m by 16.1 m
GD349DH7J0Doorway2.56 m by 3.22 m

More in Mexico

Place and region from Wikidata, described on Wikipedia; nearby town from GeoNames, under CC BY 4.0.