Glad to see you’re also adopting the size of Belgium as a unit of measurement! Although a tad unconventional, you’re not the only one using it; see The Size Of Belgium 
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It is ! 
But since we never know if the data has been mapped on purpose one should always ask the mapper if the edit was intentionally.
Maybe it’s an idea to send a automatically generated “question” to the mapper?
“You sure this 55 km² tree is what you want?”
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Cleaned up that area of plenty of benches 
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I’ve cleaned up several of the largest buildings and the biggest car park.
Thanks for compiling this list, awesome!
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…gone as well, as a landuse=construction instead of building=industrial.
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Just skimming through some of the top tags with over a million ways, some interesting ones might be:
landuse=farmlandamenity=parking_spaceleisure=swimming_poolleisure=parkleisure=garden
And if you can do linear distance instead of area:
highway=footwayhighway=steps- (Really, probably most of the
highway=values might be interesting) service=drivewaybarrier=fencebarrier=wallbridge=*tunnel=culvertnatural=tree_row
Just brainstorming because you asked; I personally probably wouldn’t be doing anything with the data.
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Great idea, looking for unusual sizes unearths a ton of anomalous features. There are loads of tiny “houses” that in reality are sheds or garages (or massive industrial buildings at the other size extreme). I’ve also seen ping-pong tables tagged as sport=tennis, which then erroneously show up as “tennis courts.” Likewise, some super-sized “swimming pools” reveal themselves to be swimmable lakes or aquatic centers (with multiple individual pools).
Inspired by this thread, I implemented 4 new filters in GeoDesk for Python, which select features based on their minimum/maximum area or length. These are now part of Version 0.1.10 (pip install geodesk -U).
So, for the houses example above, you can use:
world("a[building=house]").max_area(35).map.show()
The maximum value is specified in (square) meters, but you can also specify an explicit unit (feet, miles, etc.), e.g. max_area(feet=300)
If you want to be able to navigate to the current object on OSM when you click on a marked feature, add a link attribute to map, like this:
.map(link="https://www.osm.org/{osm_type}/{id}").show()
Or, to open features directly in the iD editor:
.map(link="https://www.osm.org/edit?{osm_type}={id}").show()
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I tidied up “building:levels”=“222222” earlier. 
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Thanks, that’s very cool. It was Geodesk that inspired me to make this list, because it’s so easy to iterate over features and calculate their area.
I did the above just for fun but if we find any systematic errors that are easy to correct from aerial imagery, then we could create Maproulette challenges similar to how TomTom does it for unusually small features.
Good idea, unfortunately I can’t create such a permanent link programmatically because I don’t have the object version number. They get thrown out when the planet files are converted into GOL files for use with Geodesk.
The World's biggest areas of farmland
| Object | Name | Area |
|---|---|---|
| Relation: 3030972 | OpenStreetMap | None | 10239.08 kilometer² |
| Relation: 13249753 | OpenStreetMap | None | 8786.77 kilometer² |
| Relation: 16632214 | OpenStreetMap | None | 7959.01 kilometer² |
| Relation: 12629505 | OpenStreetMap | None | 7761.84 kilometer² |
| Way: Beetaloo (844465251) | OpenStreetMap | Beetaloo | 7222.46 kilometer² |
| Relation: 14093640 | OpenStreetMap | None | 6949.81 kilometer² |
| Relation: CORFO (11171108) | OpenStreetMap | CORFO | 6046.61 kilometer² |
| Relation: 1299215 | OpenStreetMap | None | 3527.62 kilometer² |
| Way: 170433407 | OpenStreetMap | None | 3409.70 kilometer² |
| Relation: 2880905 | OpenStreetMap | None | 3200.33 kilometer² |
The no. 1 is half the size of Wales (sorry Belgium!)
The World's biggest parking spaces
| Object | Name | Area |
|---|---|---|
| Way: Springview Estates (1119870531) | OpenStreetMap | Springview Estates | 158341.07 meter² |
| Way: شرکت حمل و نقل سیمان دلیجان (514017924) | OpenStreetMap | شرکت حمل و نقل سیمان دلیجان | 119812.60 meter² |
| Way: 206766430 | OpenStreetMap | None | 90541.72 meter² |
| Way: 1119414725 | OpenStreetMap | None | 51381.61 meter² |
| Way: 206766375 | OpenStreetMap | None | 48943.20 meter² |
| Way: 1231199807 | OpenStreetMap | None | 46205.45 meter² |
| Way: 1156940040 | OpenStreetMap | None | 45369.29 meter² |
| Way: 304049083 | OpenStreetMap | None | 43442.71 meter² |
| Way: 410545295 | OpenStreetMap | None | 41878.33 meter² |
| Way: 1162510621 | OpenStreetMap | None | 41357.09 meter² |
Looks like most of these should be parking or depot?
The World's biggest swimming pools
| Object | Name | Area |
|---|---|---|
| Relation: Baixio (2253903) | OpenStreetMap | Baixio | 655127.68 meter² |
| Relation: Baixio (2253149) | OpenStreetMap | Baixio | 558108.41 meter² |
| Relation: Baixio (2253084) | OpenStreetMap | Baixio | 549472.54 meter² |
| Relation: Baixio (2253876) | OpenStreetMap | Baixio | 391976.92 meter² |
| Relation: Baixio (2258602) | OpenStreetMap | Baixio | 385251.34 meter² |
| Relation: Baixio (2253829) | OpenStreetMap | Baixio | 382170.08 meter² |
| Way: 662631534 | OpenStreetMap | None | 228031.25 meter² |
| Way: Watersportbaan Tilburg (125345583) | OpenStreetMap | Watersportbaan Tilburg | 157417.53 meter² |
| Way: Surwolder Freizeitsee (131907654) | OpenStreetMap | Surwolder Freizeitsee | 140654.90 meter² |
| Relation: 9468642 | OpenStreetMap | None | 116907.15 meter² |
The World's biggest parks
The World's biggest gardens
| Object | Name | Area |
|---|---|---|
| Relation: 15689617 | OpenStreetMap | None | 65.76 kilometer² |
| Relation: Hantam National Botanical Garden (15654771) | OpenStreetMap | Hantam National Botanical Garden | 60.44 kilometer² |
| Way: 1151418996 | OpenStreetMap | None | 35.44 kilometer² |
| Way: 1152878185 | OpenStreetMap | None | 29.81 kilometer² |
| Way: 1160185157 | OpenStreetMap | None | 23.14 kilometer² |
| Way: Brookgreen Gardens (427566713) | OpenStreetMap | Brookgreen Gardens | 17.00 kilometer² |
| Way: 1156064417 | OpenStreetMap | None | 15.25 kilometer² |
| Way: 240596834 | OpenStreetMap | None | 15.24 kilometer² |
| Way: 1155381865 | OpenStreetMap | None | 13.93 kilometer² |
| Way: 1156265452 | OpenStreetMap | None | 13.49 kilometer² |
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For completeness, QLever indexes features by area (apparently in hectares). As of writing, QLever is current as of March 21, so the 500 biggest benches don’t account for recent edits. So I started looking at some other superlatives that haven’t gotten as much attention.
Would we call each of the 500 largest ponds ponds? Do you all have a different definition of pond across the pond?
Of the 500 smallest parks, the smallest manages to cram all the amenities required of a city park in less than 9 square centimeters. The current official recordholder comes in at a mere 34th place, soon to be 35th:
Some of the 100 largest windmills don’t have particularly wind-millable shapes:
To find more unlikely windmills, I tried ranking them by Polsby–Popper compactness, figuring that a windmill ought to have a sturdy foundation.[1] The least compact windmill appears to be the result of someone mapping the blades as they lay on the ground:
Now let’s see how well we draw circles. For kicks, let’s pretend that junction=roundabout and junction=circular are actually supposed to be round and circular, respectively.
Incidentally, the Polsby–Popper test is a good measure of political gerrymandering. ↩︎
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See also this 437437425.61 meters tall tree in Australia.
(Yes, I fixed it)
I simply looked for height tags that started with 5 or more numbers.
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What’s even better is that it was mapped by “SanityChek” Changeset: 49391786 | OpenStreetMap
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I’ve just converted most of those to boundary=national_park or protected_area, as appropriate.
I’m at loss for appropriate tags for this one, so I left it alone. Here’s its website:
Basically, it’s a forest containing a camping ground and many ATV trails, which is the main activity in this park. It’s hardly a leisure=park, and the best fit I can think of is a landuse=recreation_ground. But I left it alone for the time being.
Judging from the Bing imagery, the shape of the first one seems to match the actual shape of the foundation.
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Great idea! I think such plausibility checks are very helpful to find wrong tagged objects.
For the bench in particular, there are several attempts to build the longest bench in the world. Would be awesome to get rid of all wrong benches until your list shows all the attempts of building the longest bench… Hmm, I just realized that it’s according to the wiki it’s not recommended to tag benches as area but only point or way are suggested. I guess your script will not find ways?
Btw: have you considered publishing your script?
Edit: I just found that overpass can determine the length of a way. If someone interested, this is the query: way(if: length() > 100)["amenity"="bench"]({{bbox}});
right!
its called footprint
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Exactly. In Nederland it’s called “standaardmolen”, literally “support mill”.
It’s a support structure with a mill building on top. The whole building can rotate on the support.
I’ve been playing around with that and it’s even easier than running my script!
This sort of query is also useful for finding examples where people put a “main tag” when they clearly meant a “side tag”: many of the biggest areas with amenity=toilets are probably campsites, supermarkets etc. with toilets, so a better tag would be toilets=yes. Same for defibrillators, but I think we don’t have a (documented) “side tag” like defibrillator=yes that just says this shop/amenity/POI has a defibrillator somewhere.
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