Mercer’s 2010 Cost of Living survey has ranked the top 10 most expensive cities in the world as follows:

1. Tokyo
2. Osaka
3. Moscow
4. Geneva
5. Hong Kong
6. Zurich
7. Copenhagen
8. New York
9. Beijing
10. Singapore

The Mercer survey covers five continents and 214 cities. It measures the comparative cost of 200+ items, including food, housing, clothing, transport, clothing, household goods and entertainment. It is the world’s most comprehensive cost of living survey.

New York is used as the base city for the index. Currency movements are measured against the US dollar. The cost of housing plays an important part in determining where cities are ranked.

Wealthy Greeks having been buying luxury houses in UK and now account for 6% of luxury house purchases over 2 Million Pounds (about $3 Million US Dollars), double the average of the past three years, as they try to protect their assets from the country’s debt crisis.

“There has been a real trend for wealthy Greek families to invest in U.K. property for a variety of reasons, but the safe haven driver is a big one,” Rupert des Forges, a partner in Knight Frank’s Knightsbridge office, said in the statement. “Greek buyers have been especially active and have been competing hard for the limited number of high-quality properties currently available.”

However, buyers of such properties should note that most luxury properties in the market are often 20+ years old and are in need of major renovations, specially in energy saving improvements. “In the past few months we have seen a surge in business, from several new luxury home owners in the UK” says Jason Smith, a representative of Central Scotland Joinery, who supply and fit conservatories, doors and double glazing in the UK and Scotland markets.

The crisis in Greece has raised questions for investors about whether the euro can survive the most serious crisis in its short history. German Chancellor Angela Merkel said today that the future of the euro is at stake, as she tries to overcome domestic resistance to the billions of euros Germany is contributing to the bail-out.

Unlike many other large cities across the world, the real estate market in Mexico City hasn’t experienced an especially sharp downturn. While prices have dropped from their peak last year, the loss of value has been small, in the neighborhood of 2.5% to 6.5%. Because the market is largely both local and cash-based (the country doesn’t have a formal mortgage system), the downturn in the global economy has had less of an impact here.

However, the decrease in value of the peso means that real estate in Mexico City is now more affordably priced for foreign buyers looking to take advantage of a relatively stable market. Many affluent neighborhoods, such as Polanco and Coyoacán, are particularly attractive to buyers from North America, Spain, France, and China, among others. The prices in neighborhoods such as these start as low as $200 per square foot, though they rise quickly from that point.

Like many countries around the world, the real estate market in Spain has been hit hard by the current financial crisis.  It is estimated that there are as many as 1.2 million new homes sitting on the market unsold, many of which have yet to be completed.  In some spots that are more popular for those purchasing vacation homes, including the Costa del Sol region, the market peaked as early as 2004.  Recent months have seen a significant wave of foreclosures, with more expected to follow.

However, the luxury home market in Spain hasn’t seen as dramatic an impact as other segments of the market.  It is estimated that these homes have only dropped 15% to 25% of their value since they hit their peak.  This includes more unusual homes or those that have a unique historical appeal.  It is likely that the prices have held up better because wealthier buyers aren’t as dependant on financing. Many of these sellers are also more likely to be able to hold onto the properties until the market improves.

The amount of money that you’ll have to shell out for truly luxurious real estate depends largely on where you happen to be.  This should be a surprise for very few — as the old saying goes, location is everything when it comes to property.

For the second year in a row, the most expensive location in the world is the city of Monte Carlo.  The average price for housing in the city is around $4,420 per square foot.  This comes as no surprise to the publisher of globalpropertyguide.com, the firm that provided the report.  Monte Carlo is a favorite location of the rich because it is one of the best tax shelters in the world.  When you add in the fact that the city is small and space is limited, the exorbitant prices make much more sense.

Still, the fact that the average price of housing in Monte Carlo is more than that of the second and third cities on the list combined (an average of $1,937 per square foot for Moscow and $1,928 per square foot for London) is an impressive achievement. Also surprising is the fact that New York dropped from the second spot to the sixth spot in the course of a year.  This is primarily due to growth in the Asian real estate markets.