Mohamed Atta
Atta was born in 1968 in a small town in Egypt's Nile Delta. He was 10 years old when he moved with his family to the Abdeen section of Cairo. Atta studied architecture at Cairo University, graduating in 1990, and continued his studies in Germany at the Hamburg University of Technology. In Hamburg, Atta became involved with the al-Quds Mosque, where he met Marwan al-Shehhi, Ramzi bin al-Shibh, and Ziad Jarrah, together forming the Hamburg cell. Atta disappeared from Germany for periods of time, spending some time in Afghanistan, including several months in late 1999 and early 2000 when he met Osama bin Laden and other top al-Qaeda leaders. Atta and the other Hamburg cell members were recruited by bin Laden and Khalid Sheikh Mohammed for the "planes operation" in the United States. Atta returned to Hamburg in February 2000, and began inquiring about flight training in the United States.
Mohamed Salah Ben Mrad
Born in the Medina of Tunis near the Tourbet el Bey, Mohamed Salah was the son of the Hanafi Bach-mufti, Sheikh H'mida Ben Mrad, a specialist in rhetoric and the elder brother of the sheikhs Neji (who served as qadi and mufti) and Brahim Ben Mrad (who served as imam,teacher at the Zaytuna,judge at the Tunis tribunal). He came from a family of Tunis scholars and intellectuals of Ottoman origin, from Turkey. Dating back to the seventeenth century, his grandfather Murad Khodja was part of the military army of Sinan Pasha, who participated in the battle of La Goulette against the army of Charles V in 1574. 
He completed his studies at the Zaytuna and left in 1900.