The imposing orphanage looms on the edge of Islamabad, housing 250 poor boys from across Pakistan who receive tuition, board and meals, and daily instruction in Saudi-style Islam.
A plaque over the doors identifies the generous benefactor: the International Islamic Relief Organisation, a government-sponsored charity from Saudi Arabia that the US accuses of spreading extremism and funding al-Qaida.
America may be widely despised in Pakistan – a new poll gives it 12% approval, but there is far greater tolerance for Pakistan's regional ally, Saudi Arabia, in all its controversial manifestations.
Saudi influence is pervasive, from the soaring minarets of Islamabad's Faisal mosque – the largest in Asia – to the corridors of power, where Saudi officials enjoy privileged access. In the past decade Riyadh has subsidised Pakistan's oil supply, offered gilded exile to the opposition leader Nawaz Sharif, and even attempted to solve its extremist woes.
When trouble erupted at the hardline Red Mosque in Islamabad in 2007, the Saudi ambassador was drafted in to broker peace.
But Saudi money and influence have attracted hostile scrutiny from western countries, particularly the US. Worries centre on a flood of charity donations, mainly earmarked for education, some of which finds their way into weapons and military training.
A senior western official in Islamabad said the main worry was Saudi funding for Lashkar-e-Taiba, the Pakistani militant group responsible for the 2008 Mumbai attacks. Funding appeared to have stopped since the Mumbai attacks, he said, but the group continues to solicit private money from conservative Saudis under the guise of charitable donations.
The IIRO has also come under scrutiny. In 2009 the US secretary of state, Hillary Clinton, privately warned that US intelligence had discovered the IIRO and two other state-backed charities "continue to send money overseas and, at times, fund extremism overseas", according to diplomatic cables released through WikiLeaks.
Files from Guantánamo Bay published this year show at least six detainees had been employed by IIRO, which US officials described as a "tier one terrorist NGO".
The accusations are denied at the Islamabad orphanage. "Our only business is education", said one employee who declined to be named. "We educate young boys, send them back into society, where they perform well."
Saudi money has been flowing into Pakistan since the 1980s, when state and private donors funded an explosion of madrasas. Many come from the Ahle Hadith school of Islam, a strict version of the faith that is close to the Salafist faith taught in Saudi Arabia.
The amount or nature of donations is shrouded in secrecy, as most come through the undocumented hawala traders, although a western official estimated it at "tens of millions of dollars".
Saudi Arabia's defenders say they are being unfairly maligned as terrorists. "Pakistan and Saudi Arabia have had exemplary relations since the day our country was born," said Maulana Abdul Aziz Hanif, vice-president of the Ahle-Hadith community in Pakistan.
The faith was growing in popularity, Hanif added, with "thousands" of mosques across Pakistan – the Punjabi city of Gujranwala alone has 500. He denied ties with Lashkar-e-Taiba, which fights in the name of the faith. "We want nothing to do with them," he said.
Secular critics say Saudi money and influence have had a corrosive influence on Pakistani society, encouraging a tide of conservatism: more veiled women, Islamist televangelists, and public shows of piety than ever before.
"All this hardline Islam is traceable to Saudi Arabia," said Pervez Hoodbhoy, a physics professor and outspoken critic of what he terms "Saudisation".
He recently published a picture showing a group of female students at his university in the 1980s, all bare-headed. A picture taken recently shows a cluster of heavily veiled females.
Most Pakistanis are reluctant to criticise Saudi Arabia, home to Islam's holiest shrines.
And the WikiLeaks files also show the Saudis have stepped up cooperation with the US in flushing out militant financiers. Officials insist its charities are now strictly above board. The IIRO, for instance, played a prominent role in emergency relief for victims of last year's epic floods.
Still, some coincidences are striking. The Islamabad orphanage, set up in 2002, is not a madrasa – it follows the government curriculum. But its founding principal was Sultan Amir, a retired Pakistani intelligence officer known as the "father of the Taliban".
Amir quit the following year but continued to follow the students' progress. But last year he was kidnapped by the Pakistani Taliban after accompanying a British journalist into the tribal belt. A video of his execution surfaced early last January.
