There was a lot of arson. As well as so called 'urban renewal' or slum clearance.
The aftermath looked like photos I have seen of the aftermath of WWII, like Dresden, seriously.
I remember exploring (not burned or otherwise structurally damaged, just condemned!) red tagged buildings during a period in San Francisco when many blocks were in the process of condemnation. The Fillmore District as it was called.
Where the jazz clubs all were.
Among them were many gorgeous old houses (many were mansions, really) and art deco prewar apartment buildings that were they to have survived to today would be worth tens or even hundreds of millions of dollars.
With all sorts of stylistic art deco touches, exotic woods, marble tile floors. In SF one could buy beautiful old Victorians for one dollar, on the condition that you had to take it away.
They don't make them like that any more.
What replaced them? Nothing- for more than a decade - in SF the land just remained empty- looking like the post Hiroshima landscape. Eventually (after most of the former residents who had gotten promises of replacement housing) had mostly died, they built just hideously ugly apartment buildings there.
Thats whats there today.