The Princess Royal has unveiled the London 2012 gold medals as the one-year countdown to the Olympics began.

2010年伦敦奥运会一周年倒计时开始之际，英国长公主公布了金牌设计方案。

The medals depict¹（描述） the Greek goddess of victory, Nike, stepping out of the depiction² of the Parthenon to arrive in the host city.

Thousands gathered in Trafalgar Square where David Cameron promised London's would be the "greatest games".

Meanwhile, diver Tom Daley performed the first official dive at the Aquatics³ Centre, the latest venue⁴（场所，地点） completed.

Synchronised swimmers formed the number one for London 2012 chairman Lord Coe and International Olympic Committee (IOC) president Jacques Rogge.

At Trafalgar Square, Mr Rogge and London Mayor Boris Johnson invited the world to come to the British capital to celebrate the Games next summer.

Mr Johnson boasted that London is already so ready for the 2012 Games that "we might as well call a snap Olympics tomorrow".

Mr Cameron declared the Trafalgar Square event a "great night for London, a great night for Britain".

"This has the makings of a great British success story. With a year to go, it's on time, it's on budget," he said.

"It's about great sport, with great British athletes like Tom Daley and Chris Hoy taking part."

'Fair play'

Mr Rogge said the world's finest athletes were dreaming of competing in "this magnificent city".

"As in 1908 and 1948, they knew they would be coming to the nation that invented modern sport and the concept of fair play," he said.

With a year to go, the Olympic Delivery Authority (ODA) said construction had finished on all six of the main permanent Olympic Park venues⁵.

The £269m Aquatics Centre was designed by Zaha Hadid with the aim of being the "Gateway⁶ to the Games".