It is minus 12 degrees on a Beijing dawn and a line of 32 soldiers raise their bayonets to a rising red flag. Perhaps a thousand pilgrims have gathered to express their national pride at Tiananmen Square, the sacred heart of Communist China.
Ahead is the Gate of Heavenly Peace, from where Mao proclaimed the new People's government about 60 years ago. Behind lies the Monument of the People's Heroes and a mausoleum for Mao's embalmed body. They are two monuments of history, frozen without context, in a city designed and continually remade to forget its past.
Geremie Barme's The Forbidden City tells how a million Red Guards ushered in the Cultural Revolution against all things old with chants previously reserved for the emperor - "wansui, wansui, wansui - may he live for 10,000 years". Mao waved to them from the gate.
In Tiananmen Square the old is erased and reborn. It pays to bring some memory guides. Especially this year.
It is about 20 years since the Chinese people claimed Tiananmen Square for themselves. Today, those at risk of not remembering to forget are watched from unmarked vans. Hundreds of closed circuit cameras peer out from lamp posts. Tourists are often outnumbered by plain-clothed police.
At sensitive times like these, when the public is liable to forget to forget, the underpass walkways are closed and tourists are searched for subversive items, like unauthorised flags. At night now the square is entirely cordoned off.
The blood has long been scrubbed away, the bullet holes puttied over and the tank-tracked concrete tiles replaced as new.
The loudspeakers on the lamp posts have been upgraded since crackling out the government's ominous verdict on the night of June 3, 1989: "A serious counter-revolutionary riot has broken out in Beijing. Thugs have stolen the army's ammunition and set fire to army trucks. Their aim is to destroy the People's Republic of China."
Still, there are some who stubbornly refuse to forget.
"I glanced at the stationary tank and saw pieces of Wang Fei's trousers and leg caught in its metal tracks," writes Ma Jian in Beijing Coma. "The tank drove away, taking Wang Fei's flesh with it and leaving two tracks of blood on the road."
And there are those who have tried to forget, but failed.
My guide for the day had visited after midnight on June 4, 1989, at the south-east exit of the Tiananmen East subway station.
By then the troops and tanks had already cleared the square. She hid behind the front hedges of what is now Beijing's most formidable building, the Public Security Bureau.
Soldiers saw camera flashes from journalists either side of her and sprayed bullets from 10 metres away. Both of her anonymous comrades were shot. Unharmed, she fled home.
She has befriended the veterans of Tiananmen who have been exiled overseas. They are a community of kites with broken strings, she says, yearning for home.
Public Security officers detained her in recent years to make her talk about her friends. They smashed her lucrative business and destroyed her relationships.
"It took me two years to learn how to forget my past," she says.
But this year, the 20th anniversary, it is particularly hard to forget.