The cathedral got lucky as its skeleton, the walls, whats left after WWII fighting and bombing, were allowed to survive through the Soviet times. During 198x we

The cathedral got lucky as its skeleton, the walls, whats left after WWII fighting and bombing, were allowed to survive through the Soviet times. During 198x were was a flea/farmers market inside and behind it. The Castle didn't get that luck - https://en.wikipedia.org/wiki/K%C3%B6nigsberg_Castle https://en.wikipedia.org/wiki/K%C3%B6nigsberg_Castle. It got bulldozed, and the boondoggle of Soviet glory - the "skyscrapper" (21 story in Kaliningrad region in 198x was almost mindblowing, add to that that it is on the top of the Castle hill, so it looms large over the city) - is still unfinished and (https://en.wikipedia.org/wiki/K%C3%B6nigsberg_Castle#Current_situation https://en.wikipedia.org/wiki/K%C3%B6nigsberg_Castle#Current... ) "Continuation of development was stopped in the 1980s as the massive building gradually sank into the structurally unsound soil stemming from the collapse of tunnels in the old castle's subterranean levels. Many people call this the "Revenge of the Prussians" or "The Monster"." These underground tunnels (Kenigsberg and Prussia as whole has a lot of them) were back then and i'd guess even more today the scene of active exploration, in particular for hidden Nazi stolen treasures (e.g. "Amber room"), weapons/munitions/etc. and just out of sheer curiosity ( after all it is centuries of history starting from Teutonic Order). So you sometimes would find yourself facing a problem of "N tunnels in three dimensions" with some of them flooded/leading into unknown/etc.