Among the fast-changing trends of international cuisine, Peking Duck is a rare enduring classic, with a history stretching back 1,600 years.

Indeed, demand for the dish is so high that the most popular venues are not just single restaurants but chains of restaurants - Quanjude, for example, is listed on the stock exchange.

Quanjude (the name means 'a complete gathering of virtues') is currently top of the pops for Peking Duck but is no longer the only famous chain serving it. Da Dong, named after its chef and founder, is popular among expats and has become famous for its light and healthy twist on Shandong and Beijing foods.

The grand-daddy of them all, Bianyifang has just opened its latest branch by the 4th Ring Road in southwest Beijing, with both a modern and traditional dcor. It even has a Peking Duck museum to illustrate the history and techniques involved in the making of the legendary dish.

Bianyifang was established in 1416, while Quanjude would be founded in 1864. It is also making constant innovations to its duck dishes, including a roast duck de-greased with vegetable juice.

Other popular roast duck restaurants include Ya Wang (King Roast Duck) and Li Qun, a courtyard restaurant. For a more Western-style Peking Duck, many people visit Made in China, which offers a wide range of Chinese foods with a modern twist, with wines to match them.

But if Peking Duck were an Olympic event, it would be Quanjude that has a clear lead. Its founder, Yang Quanren, made a living 140 years ago by selling ducks and chickens at a meat market, before moving on to having his own shop. Within a year, Yang had hired several assistants and changed the old closed-oven roast method to new open-oven roasting, so as to simplify and expand production. Quanjude is now so famous it has been featured in several Chinese films and TV dramas.

Today, it issues a certificate to every customer who orders Peking Duck. The number of ducks it has roasted now exceeds 100 million, which explains why Quanjude has become a popular choice for investors since being publicly listed.

At all major roast duck restaurants, the duck is roasted upon order and sliced right next to you. It is served with slices of spring onion, cucumber, sweet brown sauce and flour pancakes to wrap the duck and side dishes into a roll. The roast duck looks temptingly golden brown and the fragrance is - or should be - irresistible.

For the more adventurous diner, restaurants often have dishes prepared with duck parts and giblets, such as quick-fried duck heart with coriander, salty poached duck liver and duck feet with mustard. The bones can also be made into a milky white tasty soup.

The success of any dish depends primarily on its great taste, and competitors are constantly experimenting to improve the flavor. Da Dong's super-lean Peking Duck prolongs the 45-minute roasting process to an hour and 10 minutes, further reducing the grease and improving the flavor. Quanjude has introduced new flavors such as mustard to accompany duck dishes, while Bianyifang adds lettuce, fresh mint, turnip and leafy sprouts. Over the years, the dish has become less oily but just as tasty.

Last year, Quanjude got a public roasting over its plan to use more electric ovens, citing them as a cleaner and more practical way of cooking. An Internet survey showed 77 percent of netizens were against the move, because fruitwood used in roast ovens had become part of the attraction of Peking Duck over the years. People worried that the famous old dish would become more like simple fried chicken. The age-old image of a master chef roasting a duck at a 6-foot-high drum-shaped oven heated with fruitwood proved resilient to the new notion of replacing it with a piece of metal. Quanjude eventually backed down.

Taste is not the only reason for Peking Duck's unique status, though. The Chinese believe that other poultry is hot in nature and therefore brings excessive heat to the body. Duck, however, is considered moderate, even slightly cold, because it comes from water and it is believed to be good for the lungs and other parts of the respiratory system. During the bird flu scare, duck sales soared while chicken suffered. Moreover, roasting duck neutralizes its innate coldness and is thought to make it a really balanced food.

So where is Peking Duck headed? Chain founder Da Dong believes it must become 'a living piece of history', combining elements of old and new. 'Today's science and technology can guarantee the efficient filtering of smoke and oil, ensuring that the fruitwood heating system meets health and environmental requirements,' he says.

Quanjude and Bianyifang are both applying for their roasting processes to be declared worthy of cultural heritage status and thus worth preserving. The two restaurants have also set up museums showcasing how Peking Duck has stood the test of time and remained a favorite food for the Chinese.

Meanwhile, restaurants like Da Dong keep in touch with master chefs from other countries, so helping to keep them in the forefront of world cuisines.

'But most importantly, we've followed the traditions of Chinese cuisine,' says Dong. 'Although we are modern and fashionable, the core of our cuisine is Chinese.'