> Why were more people than houses allowed to immigrate to Moscow? Maybe someone has some historical insight into this?

Labour demand. Moscow used to have lots and lots of factories and these factories needed workers. Increasing industrial capacity was seen as more important than providing every worker's family with their own flat right now, so stopgap measures like communal flats, dorm-style flats, hotel-style flats were used. Some are occupied to this day by people waiting for their proper flat since 1972.

I see, so it wasn't some unexpected influx. It was a deliberate decision on the part of the authorities. I guess it makes sense that industry is clustered and you often can't bring the factories to where the people live.

The 1930s time period that this discusses would have been very oddly early to begin construction of deep shelters, globally. I don't know a lot about Soviet Cold War civil defense history but Wikipedia at least confirms that dual-use construction as bomb shelters occurred during system expansions in the early 1950s, much later (and, most importantly, after the introduction of nuclear weapons). Deep shelters were not common prior to the introduction of nuclear weapons as there were cheaper and more practical defenses against conventional bombing, particularly before radionavigation (appx. early '40s).

This puts the Moscow Metro bomb shelter efforts solidly a decade later than London's conversion of Tube stations into dual-use bomb shelters, which started shortly pre-nuclear as a response to the unique challenges of defending London from the Blitz (London was highly dense and radionavigation was coming into use, largely defeating blackouts as a damage control measure). The United States made various runs at similar projects from the '50s to the '80s but they never got particularly far (which is a statement that goes generally for US civil defense efforts), probably in large part because the US never actually faced bombing like Great Britain had.

Answered elsewhere in the thread: https://old.reddit.com/r/AskHistorians/comments/lz3rj1/why_d...

Remember Russia was effectively experiencing its industrial revolution in one massive big-boom over barely 40 years. England experienced it over more than a century and still cities like Manchester ended up hugely overcrowded, with people living in squalor.

The English experience was very well-understood by socialists and communists (Marx and Engels themself had kickstarted their efforts in Manchester, after witnessing - and arguably exploiting, given their ownership of factories - the terrible conditions of the industrial working classes). It makes sense that proper housing would have been at the forefront of the industrialization efforts in the USSR, to avoid ending up in those same conditions; but industrialization itself was being pushed at breakneck speed, forever negating any progress achieved on the housing side. Hence a perennial state of "we should do something about housing!!"...

> Marx and Engels themself had kickstarted their efforts in Manchester, after witnessing - and arguably exploiting, given their ownership of factories

Marx never owned any factories - if anything he was near permanently destitute and often living off handouts from friends like Engels. A lot of his correspondence is complaining about money problems - often to Engels.

Engels family owned factories, and in fact his father sent him to Manchester to work at one to try to get him to turn away from his radical ideas, but which appears to have had the opposite effect. At several points his family basically threatened to cut him to try to get him to stop his political involvement, but kept relenting. You're indirectly right in that Engels certainly did profit via financial support from his family, and eventually, a few years before retirement, reached partner at the Manchester factory of the family firm.

I wonder if there is a website somewhere listing ordinary sites that actually double as nuclear shelters. For instance, I remember walking through the underground parking underneath Helsinki’s Kämppi shopping center, and noticing that there were huge blast doors, which were kept out of the way and made to seem unobtrusive, but could clearly be closed in some emergency.

> It's a bit surprising that this omits the fact that the Moscow Metro is a nuclear bomb shelter.

That applies to the oldest stations in the city's center. Many stations build even in 1980s are not so deep & suitable for the task, though they may have some special means integrated too.

Maybe because it is common? I mean the dual use as bunker, not the glory. I know that part of the main station of the U-Bahn in Bonn am Rhein, Germany has been built like that. Also several deeper stations built by the Hamburger Hochbahn in the 70ies are dual use like that. I guess for a certain timeframe (WW2 -> Cold War) it was like that everywhere where such infrastructure has been built?