A summer trip to the UK as a teenager and visits to Shakespeare's birthplace convinced Osama bin Laden that the west was "decadent," the late leader of al-Qaida and architect of the 9/11 attacks wrote in his personal journal shortly before he was killed by US special forces in 2011.
The journal is among 470,000 documents collected from the house where Bin Laden died that were released by the CIA on Wednesday. The agency said it had released the trove "in the interest of transparency and to enhance public understanding of al-Qaida and [bin Laden]."
Though there have been previous reports that Bin Laden travelled to the west, this is the first confirmation.
An entry in the nondescript school notebook describes how Bin Laden first travelled to "the west" for an unspecified "treatment" when he was in "sixth grade" and 13 years old.
The following year the teenager, the wealthy son of a billionaire Saudi construction tycoon, spent 10 weeks in Britain "studying". Bin Laden gives no further details, but he has previously been reported to have taken an English language course at Oxford.
In the journal, Bin Laden briefly describes visiting the home of William Shakespeare in Stratford-upon-Avon but says he was "not impressed" by British society and culture during his time in the UK.
"I got the impression that they were a loose people, and my age didn't allow me to form a complete picture of life there," he wrote. "We went every Sunday to visit Shakespeare's house. I was not impressed and I saw that they were a society different from ours and that they were a morally loose society.
The journal was bought in a well-known bookshop in Pakistan a few hours drive from the garrison town of Abbottabad, where Bin Laden spent five years with his family before his death.
The journal appears to be partially written by Bin Laden's son, Khalid, who was also killed in the Navy Seal raid, and sometimes takes the form of a question and answer session between father and son.
The journal entries are at times apocalyptic, describing the two men's dreams and visions, including a scenario in which Muslim countries unite after the revolutions and peace is established with the West - a prelude to the end times in some branches of Islamic theology.
At other times, Bin Laden appears more practical, discussing recommendations for al-Qaeda's messaging in the aftermath of the revolutions to better capitalize on rising Islamist sentiments and to take advantage of the wave of popular unrest.
Bin Laden's mention of his feelings towards the west after his time in Britain will interest experts. Most accounts of his life say he was radicalised as a student and later when he became engaged as a volunteer organiser for Arab foreign fighters taking part in the war against the Soviets in Afghanistan from around 1981.
The US government has released hundreds of documents over recent years, though this is the largest.
The US-based website, The Long War Journal, received some material in advance and reported that the documents give new details of al-Qaida's relationship with Iran.
One 19-page document contains a senior militant's assessment of the group's relationship with Iran, which describes an offer by Iran to provide some unidentified "Saudi brothers" with "money, arms" and "training in Hezbollah camps in Lebanon, in exchange for striking American interests in Saudi Arabia and the Gulf".
It is not known if the offer was accepted - if it was made at all - and the inclusion of the document will raise suspicion that one motive for the release of the new trove was to place material that casts Iran in a bad light in the public domain.
Mike Pompeo, the Trump-appointed director of the CIA, has a reputation for an aggressively hawkish stance on Iran.
It has been known for some time that scores of senior al-Qaida officials and their families were held in Iran after fleeing there in the aftermath of 2011. However the relationship between the detaine