Xi Cheng must be in her mid-80s but spins like a nimble ballerina to the tune of a lilting Chinese number. "Beijing is beautiful," she repeats. "I love the trees here and the flowers ... this is a singing and dancing park, I come here to dance everyday."

The power of the joie de vivre around her is infectious. The moment we stop to chat, a crowd swarms around and surrounds us near the gate of Tiantan, or the Temple of Heaven, one of Beijing's most famous landmarks.

Tiantan is an extensive arrangement of ancient Chinese architecture spread over 273 hectares of parkland and offers something for everyone.

Anthropologists will focus on the migration patterns of Xinjiang ethnic communities, who travel more than 1,500 km to Beijing in winter to dance on the Danbi Bridge. They all wear flame-colored harem pants and long tunics.

Sound engineers will marvel at the acoustics around the Imperial Vault, noting how a north-facing person standing on the central axis can be heard from behind the two halls on either side, 60 m apart.

And the thousands of everyday tourists will delight in getting togged up in Qing Dynasty costumes to be photographed sitting on a replica of the imperial throne.

Former US Secretary of State Henry Kissinger visited the site 14 times, but perhaps skipped the costume picture booth.

"Tiantan is more a political place than a temple," says Lu Yuxin, who has worked as a guide for about 12 years. "This was the only place where the emperor had to kowtow to a higher authority, in all other places he was supreme."

But the occasion was hardly a leveler. The elaborate rituals of fasting, change of clothes, animal sacrifice and playing of sacrificial music were performed in their designated areas, strictly off-limits to the public.

Begun in 1420 by Ming Emperor Yongle, the park was opened to the masses only in 1912. Two years later, General Yuan Shikai performed the last animal sacrifice in his bid to take on the role of the emperor. He died soon after.

During its imperial heyday, the sanctity of the temple grounds was taken very seriously. When the Hall of Prayer was struck by lightning in 1889, it was seen as divine punishment for allowing a caterpillar to crawl over the golden ball on its three-tiered roof. Thirty-two court dignitaries were executed for the lapse.

The ruined hall was totally rebuilt from scratch on the lines of the original Ming design. It has since seen several renovations, the last of these in 2005-06.

Built under Taoist "yin and yang" principles, the complex sits perfectly on Beijing's north-south axis, which cuts through the Forbidden City and travels further north to the Beijing Olympic area.

Almost 600 years after its construction, the Temple of Heaven dictated the location of the futuristic Bird's Nest and the luminescent Water Cube.

The idea of yin and yang - as in the binaries of light and darkness, positive and negative, circular heaven and square earth - also manifests itself in the people that it attracts.

The carnival of merry seniors exercising on parallel bars, moving in sync to the rhythm of tai chi or just having fun, kicking around a plumed jianzi (Chinese version of the shuttlecock), is almost evenly weighted by batches of schoolchildren clutching their satchels and exercise books, trying to get a look in through the cluster of human heads that seem to perennially crowd around the building entrances. There are no doors, but the interiors are cordoned off from the public.

The Temple of Heaven is probably the most ingenious example of a round edifice fitting happily into a square hole. The giant three-tier cylindrical structure of The Hall of Prayer for Good Harvests, mounted on a triple-layer marble altar, is set in a square courtyard. This pattern is repeated in the Imperial Vault, balanced on either side by the Echo Walls and again in the Altar to Heaven.

Taoists thought of the heaven as round and the earth as a square. So when the emperor, the intermediary between the heavenly beings and the mortals on earth, needed to solicit a good harvest on behalf of the earthlings, the place he chose to pray at, fittingly, reflected the metaphor of the meeting between earth and sky in its structural arrangement.

Tiantan is also a numerologist's ultimate fantasy. Each circular platform leading to the Hall of Prayer is nine steps above the last - nine being the highest positive single digit. The golden-tipped hall is 32 m high, is propped up by 28 pillars and no nails have been used in its construction. Four of the pillars are embossed with images of golden dragons, representing the four seasons, the 12 pillars surrounding them symbolizing 12 months, and the 12 outer ring pillars, the 12 divisions of day and night.

The obsession with numbers is taken to its height at the Circular Mound Altar. A single block of flat circular stone, where the Emperor would stand in the moment of his holy communion with the gods, stands atop three terraces, each approachable by four flights of stairs. The small marble disc is surrounded by blocks of artemisia leaf gray stones, spreading out in concentric circles, the number of slabs increasing in multiples of 9.

If the Forbidden City is the world's biggest siheyuan (courtyard residence), the giant barn-shaped Hall of Prayer for Good Harvests inside the temple grounds looks like its biggest granary.

At a time when the world's gaze is turned toward China, looking for some answers to sustaining livelihoods during a global economic crisis, the comparison assumes an added significance. Like Xi Cheng and her old friends, we live in hope.