Figures from the guide reveal that apartment space in the Principality now sells for EUR24,900 per square metre, or just under EUR3 million per 120 square metres.

Monaco's prices are being driven higher as growing demand from a flock of foreign millionaires, particularly from the United Kingdom, seek out its unique benefits as one of lowest of the low-tax jurisdictions in the world, while being only a couple of hours flying time from London. Add in the constraints of Monaco's size at not much more than 1km square, or 485 acres, and it is hardly surprising why property prices have gone through the roof in recent years.

According to travel guide yourmonaco.com some Monaco property buyers are already paying nearly US$1 million for studio apartments. The travel guide also predicted that there is only one way which prices will go in the next few years - up - and it has cited one survey which predicted a four-fold increase in the ranks of British millionaires over the coming years. Another survey forecast a 70% increase in property prices over the same period.

Ever since Monaco lost about half its territory to France in return for independence 150 years ago, it has sought ingenious ways in which to expand its territory, typically only by a few square metres at a time on land reclaimed from the sea. The principality has however recently announced a new ten-year multi-million euro plan to increase its territory by about 5%, the equivalent to more than a dozen football pitches, with the construction of a new floating "offshore" district off the coast of Monte Carlo. While the project is expected to increase the 32,000 population by about 4,000, it is unlikely to rein in the principality's run-away real estate prices.

Closely following Monaco on the Global Property Guide league table is London. Flats and apartments in prime locations in London are now costing EUR14,522 per square metre, or almost EUR1.75 million per 120 square metres. However, this is about double the amount you would expect to pay in more non-exclusive areas of the capital, where flats typically sell for EUR7,200 per square metre, or EUR863,880 per 120 square metres. According to the Global Property Guide, the large difference is explained by London’s highly segmented top-end market, with super-luxury apartments in absolutely prime areas commanding considerable premiums. Nonetheless, flats in London's less exclusive neighbourhoods are still the third most expensive in Europe in terms of price.

Paris and Amsterdam follow London, and a 120 square metre apartment in either of these cities has an average purchase price of EUR800,000 (EUR6,667 per square metre), the guide said. Rounding out the top ten were Vaduz, Liechtenstein (EUR760,000 per 120 sq m); Moscow (EUR751,920); Rome (730,000); Zurich (712,020); Oslo (614,000); and Dublin (EUR600,000).

The guide also noted that the Baltic states have accelerated quickly up the price ladder and can now be considered expensive. A high-end apartment in central Vilnius, Lithuania will cost on average around EUR3,792 per square metre (EUR455,000 for 120 sq. m.), with high-end apartments in central Riga, Latvia, costing an average of EUR3,020 per square metre.

But there are still some bargains to be had, the guide informs, with Berlin a notable example. Here apartments can be bought for about EUR3,167 per square metre (EUR380,000 per 120 sq m.) and the city is now said to be seeing large inflows of foreign money into its property sector. However, the guide points out that parts of Central and Eastern Europe are much less inexpensive, such as Warsaw (EUR1,175 per sq. m.); Bratislava, Slovakia (EUR1,292 per sq. m.); Skopje, Macedonia (EUR1,125 per sq. m.); and Chisinau, Moldova (EUR917 per sq. m.).

In terms of rental yields the Global Property Guide reports wide differences throughout the continent. Chisinau offers the best yields in the survey, at 14.13%, while Monaco offers the least attractive yields at 2.43%. Most of the higher yields are to be found in the east, such as: Warsaw (13.28%); Sofia, Bulgaria (10.56%); and Bratislava, Slovakia (10.06%). The higher risk factor is seen as the driving factor in these parts. Some Western European cities also have good rental yields: Amsterdam and Paris (8.25% in both), Munich (7.80%) and Brussels (7.53%), but the guide warns that these can all be classified as 'high tax' countries.

On a cautionary note, the guide concludes that the fact rents are failing to keep pace with prices is "a cause for concern" and considers yields falling below 4% to be a "danger signal."