From the novel I am currently reading:

Back in his hotel room he remembered that Mohammed Atta , the famous World Trade Center hijacker, had been a student of urban planning in hamburg in Germany. Was there a connection between the two things – terror and planning? It was possible. Atta in his religious way, had wanted the perfect religious city &emdash; his thesis was on Aleppo in Syria. In the end though his urge to design took a different form &emdash; het took down the twin monstrosities of the towers over Manhattan, and there, in a single day he accomplished what no other planner could have, erasing the cold shadows of those vile boastful buildings of the sun-filled streets of the city.

While “the association of small bombs” is a work of fiction it appears that the fact that Mohammed Atta has indeed written his thesis on Aleppo is not. Given this the recent events in Aleppo, which have lead to the almost complete destruction of the city, feel like the completion of a circle of violence that has been started by Atta and his companions on 9/11¹. It is probably vain hope to expect this to be the end of the circle, but with the whole geo-political situation changing quite dramatically, nothing seems impossible these days.