Every hour is peak hour at Yao's Chao Gan restaurant.

The line streams outside the building for several twists as the clock strikes 11 am.

The eatery next to the southeast corner of Beijing's Drum tower offers representative Beijing fare, including the No 1 seller, chao gan – pork livers, lungs and intestines served in a thick broth with minced garlic - from which the restaurant takes its namesake.

The 300-sq-m restaurant became world famous overnight when US Vice-President Joe Biden paid an unnotified visit last August.

It has received new tidal waves of visitors since an Internet rumor spread that it will be torn down in the renovation of the area surrouding the drum and bell towers.

The first phase won't touch the establishment, 58-year-old second-generation owner Yao Yan says.

"But I can't say the same for Phase 2."

Yao recalls growing up in the area, which chockablock with toy stores and snack shops. The sounds of bargaining in Beijing dialect dominated what was then one of the city's six busiest areas.

Her father, Yao Moxian, started the business when he saw the long lines in front of temporary breakfast stalls. So he decided to jump in the business in 1989, at age 76.

It sold chao gan and stuffed steamed buns in a 20-sq-m private house with just four tables. But it quickly became too popular for only being able to seat 10.

"Customers ate outside with umbrellas on rainy days," Yao Yan recalls.

"Even in cold winter, they stood outside and used bicycle seats as dinning tables."

In 2000 the Yao family rented the 100-sq-m neighbor house for the restaurant and expanded to 300 sq m in 2008.

Yao Yan says the restaurant has become a fixture of local residents' collective memories.

Houses in the south Drum Tower area across the street were demolished a few years ago for subway construction. But relocated residents often return to the restaurant to recall good old days, Yao says.

Ma Shuqin rides her bike for an hour to the eatery on weekends from her home near outside the Fourth Ring Road.

She always orders chao gan and steamed stuffed buns, although the options are many.

She takes home douzhi, a traditional fermented Beijing drink made from ground beans.

"I've been eating here since the day it opened," Ma says.

"I'll follow it if it moves."

Its allure is growing among new customers, as more tourists visiting the drum and bell tower know its reputation, Yao says.

Zhang Chi, a 22-year-old migrant worker from Anhui province, brought his friend Xiao Hui to the restaurant for Xiao's first trip to Beijing as part of their "most original Beijing tour".

"The flavor's a bit heavy for southerners like us," Zhang says.

"But it’s original. It is what it is."

Another eatery that has become a fixture of the neighborhood won't survive the first relocation, its owners say.

Ren's Bao Du has bleated Peking Opera from its loudspeaker since its 1986 opening.

"If I can't find another place, my only choice is to close," 59-year-old owner Ren Zhiqiang says.

If the place closes, Ren's family is out of work.

But Yao's eatery has around 30 employees. Those that aren't family members are migrant workers.

Zhu Junwei and Gu Xiaoying, a couple from Gansu province, have worked at Yoa's Chao Gan for more than five years.

"We count on this job," Zhu, 32, says.

"If we lose it, we also lose our free meals and housing."

Yao plans to open a new branch near Beixin Bridge in Dongcheng district.

The 400-sq-m establishment is decorated in traditional style and customers can order from their seats without lining up. But quality and prices will be the same, Yao says.

"Our current space can't accommodate demand," Yao says.

"More importantly, I have to ensure there's a place for our employees to go if the demolition happens."

Yao hopes her restaurant can reopen in the Drum Tower area after the renovation.

"The drum and bell tower area is to Beijing what the City God Temple to Shanghai and the Confucius Temple to Nanjing– the locus of original food culture."

Yao says of the UNESCO World Heritage List application to include the Beijing Central Axis needs to include more than the towers.

"This isn't about protecting two buildings," she says.

"It's about protecting the style of the area surrounding them and traditional Beijing life."

While Yao looks to the past and present, her 36-year-old nephew looks to the future.

"We hope Yao's Chao Gan will become a century-old restaurant."