By Avril Ormsby

LONDON (Reuters) - When the curtain goes up on the Olympic Games on Friday it will confirm London's place as the only city to host the summer sporting spectacle three times.

But could it be a Games too far?

London hopes to show off the city as a dynamic 21st century metropolis with shiny new buildings, nestling alongside the historic capital of Shakespeare and Dickens with its palaces and cathedrals.

For some critics, though, the Games represent a poisoned chalice.

"London would, in a perfect scenario, wish to convey to the world that this is an historical city but a city equipped to face the 21st century," Ellis Cashmore, professor of culture, media and sport at Staffordshire University, said.

"But this is the wrong stage in history and the British don't do these things very well."

London politician Andrew Boff said London 2012 was "one Olympics too many".

"It always was an Olympics we did not really need," he added. "London is not a city that needs to be put on the map."

The Games has cost the British taxpayer more than 9 billion pounds ($13.97 billion)at a time of economic downturn, when Britons have had to tighten their belts and they have seen public services pared to the bone.

Public resentment against the Games has been heightened by concerns about how an already cramped and creaking transport network, some of which dates back to the 19th century, will be able to cope with an additional million passengers a day.

Some of that ire will also be directed at the specially designated Games Lanes which open on Wednesday, designed to whisk 82,000 athletes, officials, dignitaries, media and sponsors to stadiums on time, but which will exclude other motorists and taxi drivers.

The threat of strikes by some train drivers and border staff have added to the perception of a city overstretching itself.

TIGHT SECURITY

The capital is also threatened with a security lockdown, as many of the world's leaders and top dignitaries, including first lady Michelle Obama, arrive for the opening ceremony.

Security was always going to be an issue after four suicide bombers killed 52 commuters on London's transport network the day after the capital was awarded the Games in July 2005.

Tensions were also going to be high as 2012 is the 40th anniversary of the 1972 Munich attack by Palestinian militants that killed 11 Israeli Olympic team members.

The Games also face a potential threat from dissidents unhappy with the Northern Ireland peace process.

Britain is to deploy an array of air, navy and military defenses, raising questions about civil liberties. Residents in east London, near the Olympic Park, have tried to prevent missile batteries being placed on the roof of their apartment block, without success.

Up to 9,000 extra police will be walking the streets of London, while more than 17,000 troops will be deployed after a botched private security recruitment drive.

Police and politicians say they will do all that is necessary to deliver a safe and secure Games.

But the failure of private contractor G4S to recruit its contracted numbers in time to guard venues embarrassed not only the firm, but also the government and London Olympic organisers (LOCOG), coming just days before the Games were due to begin.

The story dominated headlines around the world and could damage the government's aim of using the Games to lure inward investment and tourists.

Prime Minister David Cameron has suggested the Games could generate 13 billion pounds over four years.

The official cost of the Games has trebled since its initial estimate, with some observers suggesting it could be as high as 12 billion pounds.

This is at a time when Britons are struggling with a double-dip recession, rising unemployment and severe public spending cuts. Continued...