SortStack #205 — 2026-12-31

By year · Order from earliest to most recent.

1. Emperor Hadrian orders a great wall built across northern Britain 122

   The wall ran about 117 km from coast to coast and took roughly six years to build — soldiers' letters from its forts survive, including a birthday party invitation.

2. An armistice ends the fighting of the First World War 1918

   It took effect at the eleventh hour of the eleventh day of the eleventh month. The last soldier killed, Henry Gunther, died one minute before it began.

3. The Soviet Union launches Sputnik, the first artificial satellite 1957

   The beach-ball-sized satellite weighed 83 kg and beeped for three weeks. Anyone with a shortwave radio could hear it pass overhead.

4. Humans walk on the Moon for the first time 1969

   The Apollo guidance computer had less processing power than a modern pocket calculator — and alarms from it nearly aborted the landing.

5. The Human Genome Project is declared complete 2003

   The 'complete' genome actually covered about 92% — the trickiest gaps weren't fully sequenced until nearly two decades later.

6. Nations adopt the Paris Agreement on climate change 2015

   Negotiators from 196 parties agreed to pursue limiting warming to 1.5 degrees Celsius — the gavel came down to a standing ovation in a Paris suburb.

← All puzzles · Play today’s SortStack