Königsberg · 173601 / 08

The Königsberger Bridges Problem

Seven bridges joined a Prussian city across the river Pregel. Could anyone walk through the city and cross every bridge exactly once?

Scroll to walk the city ↓

The city02 / 08

A city on a river

Königsberg in Prussia lay on both banks of the Pregel. In the middle of the town the river divided around two islands: the Kneiphof, with the cathedral, and the larger Lomse to the east.

The Altstadt and the castle stood on the north bank. The Vorstadt lay on the south bank. Four pieces of land, divided by water.

The bridges03 / 08

Seven bridges

Five bridges reached the Kneiphof. Two more joined the Lomse to each bank.

1. VI
   Krämerbrücke · Altstadt – Kneiphof
2. VII
   Schmiedebrücke · Altstadt – Kneiphof
3. V
   Grüne Brücke · Kneiphof – Vorstadt
4. IV
   Köttelbrücke · Kneiphof – Vorstadt
5. III
   Honigbrücke · Kneiphof – Lomse
6. II
   Holzbrücke · north bank – Lomse
7. I
   Hohe Brücke · Lomse – Vorstadt

The puzzle04 / 08

Every bridge, exactly once

1. Start anywhere in the city.
2. Cross each of the seven bridges once, and only once.
3. No swimming, no boats, no turning back halfway across.
4. You may finish anywhere.

Watch one attempt. It starts in the Altstadt, below the castle.

Your turn08 / 08

Three down. Four to go.

These bridges are still waiting:

Can you cross all seven, each exactly once? In 1736 Leonhard Euler took up this question. Try it yourself before you read his answer.

Walk Königsberg 1736 → 1736.koenigsberg.city