As cities get more and more expensive and unaffordable, here's a look at the four most expensive cities and the two fastest growing cities (Singapore and Los Angeles) in terms of office rentals.

London's West End, Mumbai, the City of London and Moscow are the top four most expensive office markets in the world, followed by Tokyo (Inner Central), Tokyo (Outer Central), Paris, New Delhi, Dublin and Hong Kong according to CB Richard Ellis Research's Global Market Rents survey.

London's West End

London's West End is ranked as the world's most expensive office market. At $328.91(calculated as occupation cost in US$/sq ft/annum), occupation costs are 82 per cent higher than the City of London, where occupation costs rose to $180.80, making it the world's third most expensive city.

The elite West End of London has many of the city's major tourist spots, business headquarters and the West End theatres.

Image: Traffic moves through Piccadilly Circus.