Inside the post you will see the ten best and ten worst cities of our planet, according to Mercer's 2009 Quality of Living survey.
Let's start with the best cities. So, the tenth place is going to Sydney, Australia.

10. Sydney, Australia

Australia's largest city, with a population of nearly four and a half million, Sydney's beaches, beautiful harbour and cultural attractions - including the Sydney Opera House - are its big draws, although, according to Mercer, it is the world's 15th most expensive city.

9. Bern, Switzerland

With a population of around 128,000, Bern is Switzerland's fifth most inhabited city. The medieval centre is a UNESCO World Heritage Site, while Albert Einstein once lived and worked in the city as a patent office clerk.

8. Frankfurt, Germany

The largest financial centre on the continent, Frankfurt is the seat of the European Central Bank and the German Federal Bank. The city's key sights include its 14th-century Gothic cathedral and a host of futuristic skyscrapers.

7. Munich, Germany

Germany's third-largest city with around 1.36 million inhabitants, the Bavarian capital also boasts plenty of Gothic architecture. Munich was heavily damaged by allied bombing during World War II, but recovered to host the Olympic Games in 1972.

6. Dusseldorf, Germany

Situated on the Rhine, the city is renowned as a centre for German fashion, advertising and telecommunications, while the Dusseldorf Karneval attracts millions of visitors each year. The city is twinned with Warsaw, Moscow, Cairo and Reading.

4= Auckland, New Zealand

Home to 31 per cent of New Zealand's population, Auckland boast two harbours - Waitemata to the north and Manukau to the south, helping earn its nickname: the City of Sails.

4= Vancouver, Canada

Consistently ranking among the cleanest, most livable cities in the world, Vancouver possesses an ethnically-diverse population, while it has become a centre for shipping, film production and a popular tourist destination.

3. Geneva, Switzerland

With a population of around 185,000, Geneva is best known for diplomacy (it is home to various UN and Red Cross agencies), finance and the CERN nuclear research facility - birthplace of the World Wide Web and the Large Hadron Collider.

2. Zurich, Switzerland

One of Europe's richest cities and home to a wealth of multilingual Europeans, Zurich has attracted the likes of IBM, UBS, Google and Microsoft - each of whom has offices in the city. Novelist James Joyce died and was buried in Zurich.

1. Vienna, Austria

The world's best city in which to live, according to Mercer, Vienna boasts great economic, cultural and political strength, was the birthplace of Marie Antoinette and Sigmund Freud and has been sung about by Ultravox and Billy Joel.

The worst

10. Port-au-Prince, Haiti

The Haitian capital, Port-au-Prince has around 2.5-3 million residents, many of who are concentrated in the city's numerous slums. Despite political unrest, the city still attracts some tourism.

9. Kinshasa, Democratic Republic of Congo

Among the largest sub-Saharan conurbations, Kinshasa has a population of around 8 million when combined with neighbouring Brazzaville. The city has a high crime rate with 112.3 murders per 100,000 residents.

8. Nouakchott, Mauritania

Mauritania's largest city, Nouakchott expanded from a tiny fishing town in the 1950s to become a city of nearly 900,000 residents, many of whom moved to the city to escape drought.

7. Pointe Noire, Congo

Congo's second largest city, Pointe Noire is among Central Africa's largest producers of oil. Its attractions include its surfing beaches, although the Foreign Office warns visitors to beware of carjacking and walking the streets after dark.

6. Sana'a, Yemen

Dating back to the 6th-century BC, Sana'a's Old City contains a number of ancient buildings and is recognised as a World Heritage Site. Recent attacks on foreign nationals and the bombing of the US Embassy, however, means it is off most tourist itineraries.

5. Khartoum, Sudan

Located on the confluence of the Blue and the White Nile, and the stage for Chinese Gordon's last stand, the Sudanese capital has seen a great deal of development in recent years, driven largely by the country's oil money.

4. Brazzaville, Congo

Founded in 1880 by European explorer Pierre Savorgan de Brazza, the city's major industries include textiles and tanning. There were also a number of conflicts and civil wars here throughout the Nineties.

3. Ndjamena, Chad

With a population of more than 700,000, Ndjamena was originally founded by the French in 1900 as Fort-Lamy. The city was heavily damaged during the civil war of 1979-82, while rebels attacked the city as recently as 2008.

2. Bangui, Central African Republic

Originally a French military post, Bangui became a colonial administrative centre and now has a population in excess of 500,000. The city manufactures textiles, soap and beer, while a number of archeological sites outside the city have UNESCO World Heritage status.

1. Baghdad, Iraq

Baghdad is the world's worst city in which to live, according to Mercer. Despite possessing a rich heritage, the city remains beset by problems, although the level of violence across Iraq appears to be falling.

[via telegraph.co.uk ]