With a wide semi-circular entrance hall and doormen in tops-and-tails, the apartment building at 199 Knightsbridge in London is all glass, polished marble, and clean lines. Advertised as an enclave of private residential apartments in the capital’s heart, the penthouse of the prestigious development is yet another home for Leyla and Arzu Aliyeva, daughters of the president of Azerbaijan.

It is the latest multimillion property secretly owned by the Aliyevs to be discovered, part of an empire amassed since 2003 when Ilham Aliyev took over from his father as president of the oil-rich country. OCCRP has identified over US$140 million in luxury apartments the family maintains around the globe and these are just the known properties.

Other international properties include a US$ 25 million London mansion; a flat valued at up to US$ 8 million overlooking the Speakers’ Corner of Hyde Park; nine waterfront mansions in Dubai valued at US$ 44 million; a dacha near Moscow worth at least US$ 37 million; and a US$ 1.1 million villa in an exclusive neighborhood in the Czech spa town of Karlovy Vary.

While his family tours the world as international celebrities, Aliyev rules at home with an iron fist, beating protestors and arresting and jailing democracy advocates and independent journalists including Organized Crime and Corruption Reporting Project (OCCRP) partner Khadija Ismayilova. Meanwhile the family has amassed a vast personal business empire and taken over the country’s largest businesses, including banks, construction companies, gold mines and phone companies.

The First Family is no more open about its London property holdings – including the 101-square-meter penthouse–than about its other assets. Ownership is hidden behind the mask of an offshore firm, Capper Marketing Inc., registered in one of the world most secretive jurisdictions: the British Virgin Islands (BVI).

Overlooking Hyde Park, 199 Knightsbridge is split into 205 flats. Construction was completed in 2005 and the apartments’ were reportedly marketed for between £ 750,000 and £ 18 million (US$ 1-26 million). Today they are worth more.

The penthouse in which building staff told the OCCRP that Arzu and Leyla live was purchased in September 2006. The sale was likely brokered privately, as the penthouse is nowhere to be found in online archives of real estate ads. A deed filed at the UK’s Land Registry lists no sale price.

The building is near Harrods, the high-end shopping Mecca often frequented by Eastern oligarchs. It has its own website featuring a video trumpeting an “exclusive world” built for the “discerning few”. It also boasts a 20-meter swimming pool, residents-only “kinesis spa” and a business center crowned by a 12-seat boardroom.

When an OCCRP reporter visited the building to deliver a request for comment, the concierge told her that Leyla had been in the building that day to visit the gym. On another occasion when an OCCRP reporter visited, a staffer at the delivery desk suggested Leyla had “three or four” apartments in the building. OCCRP couldn’t identify the other properties as most also are owned through offshore companies.

The penthouse was purchased just five months after Leyla Aliyeva married Emin Agalarov, a Russian pop star who is the son of a billionaire real estate magnate. They have since divorced.