Finding the gaps inside the Ring

Step 1

Draw the line

The S-Bahn Ring encircles the dense core of Berlin. Its outline happens to be an official dataset: Berlin's low-emission zone (Umweltzone) is exactly the area inside the Ring.

87 km²

inside the Ring, about a tenth of Berlin

Step 2

Every parcel

The land register (ALKIS) divides the city into parcels. Each dot on the map is one of them: courtyards, streets, river banks, cemeteries, schools, office blocks.

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parcels inside the Ring

Step 3

Remove what's built

We overlaid every registered building footprint. A parcel stays in the search only if buildings cover less than 10% of it.

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parcels nearly empty

Built parcels fade out. What remains is still mostly parks, streets and water.

Step 4

Keep what's meant to stay open

Parks, playgrounds, cemeteries, allotment gardens, schools, water, railways and streets are not building land. We removed every parcel that overlaps them, using Berlin's green-space register and OpenStreetMap.

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parcels left

Step 5

Stitch parcels into sites

Big lots are often split into many thin parcels. Luisenblock Ost, between Schiffbauerdamm and the Stadtbahn viaduct, is 19 parcels and about 3.3 hectares of gravel and parking. Each parcel alone looked like a street strip, so our first pass missed it entirely.

Now neighbouring empty parcels are merged into one site before we judge size and shape.

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candidate sites

Step 6

Look at every one

Registers lag reality. New buildings take years to appear in the land register, and a parcel listed as empty may be a courtyard garden. So each site gets checked against the 2024 aerial photo.

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sites checked so far

Step 7

What could be built

Floors follow the median height of the buildings next door, the way Berlin's planning law asks new buildings to fit in. Then it depends on how much you assume.

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apartments