By Sandra Kanthal
Producer, Alvin Hall's World of Money
Donald Trump Jr has not noticed any downturn for prestige properties
Until recently, house prices had been on a seemingly unstoppable upward spiral.
Property had become the asset of choice for both private and professional investors.
But then the credit crunch hit.
House prices across the UK and elsewhere around the globe went into free fall.
Investing in property is now the preserve only of the very brave, the very stupid or the fabulously rich.
At the top end of the market properties are still changing hands for many millions of pounds.
These high-end properties exist in a market climate all their own and for many buyers and sellers the odd 10% rise or fall in the asking price for these hard to find homes hardly makes a difference.
For the super rich the cost of one house hardly matters, as they are more than likely to own portfolios of properties around the world.
What is being bought is a way of life.
"The marketplace is all about buying a lifestyle," says Jonathan Hewlett of high end property consultants, Savills.
"Wealthy people come to London or already exist in London, they want to buy properties like we go to the shops to buy a suit or a tie and the thought of having to wait six months or three years is too much for them.
"Time is money to most of them - it's find something that's ready, let's go for it."
Mr Hewlett has been in the business for nearly 25 years, watching the market's ebbs and flows, and has seen how things have changed.
"When I started you counted on your fingers the number of £1m - and I mean £1m properties - now the market goes up to £100m.
"There are certainly quite a few sales that I have been involved around £50m."
In New York the high end goes up to sky-scraping levels as well.
Fifteen Central Park West was designed by Robert A.M. Stern
Fifteen Central Park West is one of the newest residential properties to spring up for the super wealthy of Manhattan.
It boasts private wine cellars, its own library, a private cinema screening room, and a chef on call 12 hours a day.
William Zeckendorf, who developed this site with his brother Arthur, seems quite pleased with the way sales are going.
"The apartments start at approximately $5m (£2.5m) and how high do they go? You can use your imagination but we have had many sales over $40m," he said.
"We're sold out now so we sold $2bn of apartments in about two years."
These are not small flats either so many residents decide to buy extra space to house their staff.
"We have three floors of maid suites - those are all about 600 sq ft (56 sq m) - there are some that are a 1,000 sq ft (93 sq m) and those were sold out immediately," he added.
In case you are interested, the staff quarters will set you back anything from £1.2m to £2.4m.
A name that is synonymous with luxury housing in New York is Donald Trump, and his son Donald Trump Jr has followed his dad into the family trade.
He has not noticed any downturn for prestige properties.
"The places where we are producing best are actually in our very large units - we sold a unit in Trump World Tower for $39m.
"We have an apartment in Trump Park Avenue for $45m and those are the things that are seeing the most interest, because as the economy waxes and wanes, there still tend to be people in that top one percentile.
"For them it's almost irrelevant, meaning they're not affected by the sub prime crisis - they are not worried about getting a mortgage.
"If they want, they close on their apartments," he added.
But can this buoyancy in the top of the market really last?
At Barclays Wealth Management, Michael Dicks says that buying at this level of the market might be a way to hedge one's bets against the worst of the cyclical downturn.
"It's difficult to know for sure, but probably you have more insurance, if you like, buying at that end of the market, so it's not so much of your wealth.
"It's part of your investment portfolio, but it's not a huge part.
"I think for most people, losing your job means that you struggle to meet your mortgage payments, and as a result the housing market is very sensitive to the economic cycle.
"If it's only one of your properties - or only a part of your portfolio - it may well be that you can get through an economic cycle without missing out on those payments that you owe."
The difference between the rich and the super rich has become more pronounced in the past decade, so it is not surprising that the difference in the properties in which we live would be more pronounced as well.
It seems that if you have the money to live at the top of the housing ladder you can sleep easily knowing your property investments probably are as safe as houses.
BBC Radio 4's Alvin Hall's World of Money was broadcast on Saturday, 16 August 2008 at 1204 BST, and was repeated in a longer version on Monday, 18 August 2008 at 1502.