Castles, cartel compounds, billionaire bunkers and homes once occupied by the rich, powerful and infamous have emerged in OneRoof's hunt for the most expensive residential properties across the OECD.
Some of the prestige homes we uncovered make New Zealand's priciest listing, a six-bedroom Herne Bay property at 15 Cremorne Street with a $60 million-plus price tag, look almost suburban. It is worth less than a tenth of the most expensive home currently listed for sale in the United States.
OneRoof examined property markets across the OECD to identify the most expensive homes currently listed for sale, as well as the biggest reported residential sales of 2025 and 2026.
Pinning down the top properties was not always straightforward. At the ultra-luxury end of the market, many homes change hands privately and never appear on public real estate databases, while others are marketed without asking prices. There is also a fine line between a lifestyle estate, which we included, and a working farm with a mansion attached, which we did not.
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The exercise also highlighted how modest New Zealand's residential records are on the global stage. The country's house price record, set this year when Andersons Cove sold for $56m, is dwarfed by deals regularly seen in the United States, United Kingdom and Australia.
New Zealand's most expensive listing, 15 Cremorne Street in Herne Bay, is tipped to achieve more than $60m. It is ranked 18th in OneRoof's OECD list. Photo / Supplied
New Zealand's top sale price is $56m for Anderson's Cove, in Northland - quite a bit below the top OECD sale price of $283.9m. Photo / Supplied
The most expensive public listing in the United States at the time of writing was a Bel-Air mega-mansion at 11201 Chalon Road, California, which carried a price tag of NZ$668m (US$400m), more than 10 times the value of New Zealand's highest-priced listing.
The United Kingdom and Australia, two countries New Zealand frequently compares itself with, also eclipsed the Cremorne Street listing.
In the UK, a duplex penthouse at One Hyde Park in Knightsbridge, London, was on the market for NZ$392m (£175m). Spanning 1672sqm across two levels, the apartment sits within one of the world's most exclusive residential developments.
"The penthouse is one of the finest residential real estate assets in London, offering unparalleled lateral living space, in a super prime location in Knightsbridge, with uninterrupted views over Hyde Park," Sotheby's International Realty agent Becky Fatemi wrote.
The property, which billionaire property developer Nicky Candy created, also features wraparound terraces.
"One Hyde Park is one of the most exclusive and secure residential developments in the world," she wrote.
The most expensive home for sale right now in an OECD member country is 11201 Chalon Road, in Bel-Air, California. It has a price tag of NZ$668m. Photo / Supplied
The penthouse at One Hyde Park, in London's Knightsbridge, is looking for NZ$392m. Photo / Supplied
Australia's priciest home, 2A Bayview Hill Road, Rose Bay, Sydney, can be yours for just over NZ$187m. Photo / Supplied
Australia's top public listing at the time of writing was a waterfront estate at 2A Bayview Hill Road, Rose Bay, Sydney, with an asking price of NZ$187.2m (A$150m). Overlooking Sydney Harbour, the property offers 180-degree water views and "every conceivable luxury", according to Sotheby's International Realty agent Michael Pallier.
Among OneRoof's collection of top-priced OECD listings were five genuine castles or châteaux, located in Switzerland, France, Sweden, Luxembourg and Slovakia.
The most valuable was Château El Masr, in Cologny, Switzerland, which was listed for NZ$114.4m (CHF55m). Built in 1883-84, the castle was commissioned by Scottish entrepreneur Charles Flood after he amassed a fortune in Egypt.
At the time of writing, New Zealand ranked 19th for highest asking prices in the OECD, sitting behind Germany and ahead of Hungary.
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That ranking, however, can swing dramatically on the back of a single trophy property. One ultra-luxury listing can propel a country into the upper reaches of the table, while its sale or withdrawal can send it tumbling down the rankings.
This helps explain some apparent anomalies. While most countries ahead of New Zealand in the rankings are significantly wealthier, two stood out: Türkiye and Mexico.
Both had homes listed for sale at prices exceeding New Zealand's most expensive listing despite substantially lower GDP per capita. New Zealand's GDP per capita in 2025 was about $88,000, compared with $33,000 in Türkiye and $24,600 in Mexico.
We also found foreign buyers playing a major role at the top end of many OECD property markets.
Fancy a castle? Try Le château El Masr, in Geneva, Switzerland. Photo / Supplied
Villa Bellagio, in Sierra Blanca, is the most expensive home for sale on the open market in Spain. Photo / Supplied
The impressive Silence Kamigyō-ku, in Kyōto, Japan, can be snapped up for NZ$67.8m. Photo / Supplied
The cheapest trophy home in OneRoof's OECD list is Pädaste Mõis, Pädaste, in Estonia. Yours for just NZ$8.58m. Photo / Supplied
New Zealand's Active Investor Plus "golden visa" scheme allows wealthy foreign nationals to secure residency by investing between $5m and $10m in the local economy.
What was most striking, though, was the scale of the homes on offer. Even New Zealand's most luxurious properties remain recognisably residential. Overseas, many trophy assets resemble private resorts, palaces or compounds.
Unlike New Zealand, where house sales are generally a matter of public record, many countries keep settlement prices confidential. To bridge that gap, we relied on international media reports tracking major luxury transactions. Where sale prices were unavailable, we recorded properties separately using their last advertised asking price as an indicator only.
Asking prices should not be interpreted as confirmed sale prices and may have exceeded the amount ultimately paid.
Many of the OECD's highest-priced homes also came with remarkable backstories.
In Colombia, one of the biggest reported sales was the bombed-out ruins of Pablo Escobar's notorious Medellín compound, La Manuela, on the shores of the El Peñol-Guatapé reservoir.
Pablo Escobar's empire included some of Colombia's most expensive homes. Photo / Getty Images
The 7000sqm mansion was bombed by a rival cartel in 1993 and has been deteriorating ever since. Escobar was killed later that year. Local legend holds that its walls contain hidden cash, cocaine and valuables, although repeated searches have failed to uncover any treasure.
In December 2025, the Colombian Government sold the property to an undisclosed buyer for NZ$4.35m (COP7.7bn), triggering protests from a member of the Escobar family, who claimed they would have bought it had they known it was available.
The highest-priced sale on OneRoof's Colombia list also had cartel connections. A sprawling estate in Chía, Cundinamarca, once owned by the Bogotá cartel, sold to a university for NZ$8.35m (US$5m).
Some of the world's biggest names feature in the luxury listings and record-breaking sales. Meta founder Mark Zuckerberg and his wife, Priscilla Chan, appeared twice in OneRoof's research.
Mark Zuckerberg and his wife, Priscilla Chan, have been accumulating record-breaking mansions around the world. Photo / Getty Images
Zuckerberg and Chan paid NZ$99.45m for Strancally Castle in Ireland. Photo / Getty Images
The couple reportedly paid NZ$99.45m (€51,171,155) for Strancally Castle in Co Waterford in August 2026, setting a new benchmark for a single residential property sale in Ireland that year. The Gothic Revival castle sits on 178ha and dates to about 1830, having been built for former MP John Keily.
Zuckerberg and Chan were also linked to the most expensive residential sale recorded in the United States during the period: a NZ$283.9m (US$170m) purchase of 7 Indian Creek Island Road in Indian Creek, Florida. The 2787sqm waterfront mansion reportedly includes nine bedrooms, a gym, a hair salon and a 5678-litre fish tank. Among the enclave's high-profile residents are said to be Jeff Bezos, Tom Brady and Ivanka Trump.
Another headline-grabbing deal involved former Italian prime minister Silvio Berlusconi's famed Villa Certosa in Sardinia. The estate reportedly attracted a binding €350m (NZ$694m) offer from a company linked to Qatar's Al Thani royal family in June this year.
Villa Certosa hosted an extraordinary cast of world leaders during Berlusconi's ownership, including George W. Bush, Tony Blair, Vladimir Putin and Spanish prime ministers José María Aznar and José Luis Rodríguez Zapatero.
Former Italian prime minister Silvio Berlusconi with Russian President Vladimir Putin at Villa Certosa in Sardinia in the mid 2000s. Photo / Getty Images
Formula One founder Bernie Ecclestone and his wife Fabiana Flosi are fans of expensive real estate. Photo / Getty Images
The estate itself is on a scale rarely seen outside royal palaces: about 126 rooms, seven outdoor pools, seven guest villas, a spa, football and golf facilities, a helipad, an artificial volcano, a bunker and an underground grotto accessible by small boat.
Another celebrity-linked transaction was the €40m (NZ$78m) purchase of a 2000sqm mansion in Quinta da Marinha, Cascais, by Fabiana Flosi, wife of former Formula One boss Bernie Ecclestone. The deal was reported to be the most expensive private residential transaction ever recorded in Portugal. Quinta da Marinha is widely regarded as one of the country's most sought-after addresses.
Türkiye's most valuable residential sale came with its own controversy. The property belonged to businessman Akın İpek, whose assets, including the White Mansion in Bebek on the Bosphorus, were seized by the government after the failed 2016 coup attempt. İpek, who was living overseas at the time, was accused by Turkish authorities of links to the Gülen movement, which they blamed for the coup.
After four unsuccessful auctions, the mansion finally sold in 2025. The winning bid was reported to be TL1.116 billion, including VAT, equivalent to about NZ$48m at the time.
One Hyde Park developer Nick Candy and his estranged wife, Holly Valance. Photo / Getty Images
In the UK, one of the year's most eye-catching sales had an Australian connection. Providence House, the former home of One Hyde Park's Candy and his then wife, Australian singer and former Neighbours star Holly Valance, reportedly changed hands for between £265m and £275m (about NZ$600m).
According to media reports, Candy hosted US President Donald Trump at the Grade II-listed mansion, which dates to the early 19th century and sits within the grounds of the Royal Hospital Chelsea.
The central London trophy home comes with its own lake, a vast underground swimming pool, a private IMAX cinema, an orangery and a panic room. Candy and Valance reportedly split in 2025.
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