Mohamed Atta, the eventual ring leader of the hijackers who flew his plane into the North Tower of the World Trade Center, also helped plan the scheme. Having grown up in Egypt in a strict household, he is described as having had a very serious demeanor. From a young age, he excelled at his studies and was seldom allowed to play. Although his family wasn't particularly religious, experts believe that once he moved to Hamburg, Germany, his religious beliefs intensified. Atta was known to leave the room when lurid entertainment like belly dancing came on TV, and was likely disgusted with women's revealing clothing and prostitution, both common in Hamburg [source: McDermott].
After getting a degree in architecture in Cairo, Atta moved to Germany to further his studies and ended up at the Technical University of Hamburg-Harburg. Upon arrival in Hamburg in the early '90s, he wasted no time looking for a mosque, eventually finding one called Al Quds. It was through this mosque that Atta formed a prayer group with like-minded Muslims, including Ramzi bin al-Shibh, Marwan al-Shehhi and Ziad Jarrah.
The group met at an apartment at Marrienstrasse 54. Impressed with Al Qaeda's bombing of U.S. embassies in East Africa in 1998, they soon sought involvement with the organization. By late 1999, they succeeded. After coming to Al Qaeda, the members of the Hamburg cell soon met Osama bin Laden himself. Although unexceptional and unremarkable, these members of the Hamburg cell were exactly the kind of men bin Laden had been looking for. They were dedicated and willing to become martyrs, but most importantly, they had clean backgrounds and would have a relatively easy time getting into the United States.
Bin Laden asked them to become martyrs for the "Planes Operation," which was a plot crafted by the infamous terrorist Khalid Sheikh Mohammad. The idea involved hijacking planes and crashing them into high-profile buildings. Members of the Hamburg cell were ready and willing. They soon went to work, returning to Germany, getting replacement passports, requesting visas and, finally, taking flight lessons in the United States.
With Al Qaeda supplying funding, instruction and 15 "muscle terrorists" to join them on the planes, the members of the Hamburg cell simply had to follow orders.