Gates of hell

Fengdu Ghost City

01Caesar's inner wall (contravallation) was 11 miles; his outer wall (circumvallation) was 14 miles — both built in under six weeks.
02The relief army of roughly 250,000 Gauls attacked both walls at once; Caesar personally rode to plug a breach, his red cloak used as a field signal.
03When the relief army failed, Vercingetorix surrendered 80,000 starving survivors — and the 20,000 Mandubii civilians Caesar had refused to feed died in the gap between the walls.

01Biko was transported naked, shackled, and comatose in the back of a Land Rover for 900 kilometres from Port Elizabeth to Pretoria.
02The district surgeon who examined Biko before the drive certified him fit for transport; that surgeon, Ivor Lang, was never criminally charged.
03Biko died at 30 years old, 26 days after his arrest; his death triggered an international arms embargo against South Africa.

In 1974, the Arecibo Observatory was used to send the first known intentional radio message transmission into space

01The 1974 Arecibo Message was aimed at globular cluster M13 — 25,000 light-years away, arrival date roughly 26,974 AD.
02Stephen Hawking publicly warned that contacting aliens could be analogous to Native Americans meeting Columbus — and we know how that ended.
03METI International transmitted 'Sonar' toward GJ 273, a nearby star, in 2017 without any international consensus or oversight body approving it.

In 1971, a Soviet drilling rig collapsed into a natural gas pocket in Turkmenistan's Karakum Desert. Engineers lit it to burn off the gas. It has not gone out in over 50 years.