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.