I've seen questions here about what cities would be like after being abandoned for a thousand years, but what would be left after timescales of tens of thousands of years? Ancient settlements like Catalhoyuk or Gobekli Tepe can provide some answers, but these were made from stone; buildings made from materials like concrete (reinforced or unreinforced), steel and glass are a much greater mystery to me.
In this scenario, let's assume that a monumental portion of humanity was killed by a mysterious disease, and the humans that were left decided to go nomadic rather than live with the diseased corpses. The cities were therefore left mostly untouched for the next many thousands of years, where humans are still living nomadic lifestyles. Let's also assume that over the course of these thousands of years, there have been no major catastrophes except for those that already occur on a cycle.
I am asking this question because I am unfamiliar with the effects of time on a city over such immense timescales, which many of the questions here don't cover.