From Orbital Mechanics, a visualization of the 2153 nuclear weapons exploded on Earth since 1945.
2153! I had no idea there had been that much testing. According to Wikipedia, the number is 2119 tests, with most of those coming from the US (1032) and the USSR (727). The largest device ever detonated was Tsar Bomba, a 50-megaton hydrogen bomb set off in the atmosphere above an island in the Barents Sea in 1961. Tsar Bomba had more than three times the yield of the largest bomb tested by the US. The result was spectacular.
The fireball reached nearly as high as the altitude of the release plane and was visible at almost 1,000 kilometres (620 mi) away from where it ascended. The subsequent mushroom cloud was about 64 kilometres (40 mi) high (over seven times the height of Mount Everest), which meant that the cloud was above the stratosphere and well inside the mesosphere when it peaked. The cap of the mushroom cloud had a peak width of 95 kilometres (59 mi) and its base was 40 kilometres (25 mi) wide.
All buildings in the village of Severny (both wooden and brick), located 55 kilometres (34 mi) from ground zero within the Sukhoy Nos test range, were destroyed. In districts hundreds of kilometers from ground zero wooden houses were destroyed, stone ones lost their roofs, windows and doors; and radio communications were interrupted for almost one hour. One participant in the test saw a bright flash through dark goggles and felt the effects of a thermal pulse even at a distance of 270 kilometres (170 mi). The heat from the explosion could have caused third-degree burns 100 km (62 mi) away from ground zero. A shock wave was observed in the air at Dikson settlement 700 kilometres (430 mi) away; windowpanes were partially broken to distances of 900 kilometres (560 mi). Atmospheric focusing caused blast damage at even greater distances, breaking windows in Norway and Finland. The seismic shock created by the detonation was measurable even on its third passage around the Earth.
The Soviets did not give a fuck, man…what are a few thousand destroyed homes compared to scaring the shit out of the capitalist Amerikanskis with a comically large explosion? Speaking of bonkers Communist dictatorships, the last nuclear test conducted on Earth was in 2013, by North Korea.