The 124-year-old started life as a place where physicians ministered to the poor. Years later, it became a disco, then a restaurant, before becoming the office of a company that markets aloe vera products.
The former Thong Chai Medical Institution at 50 Eu Tong Sen Street, which opened in 1892, is looking fresh despite its age.
Mr Jeffrey Chang, general manager of the aloe vera marketer - Forever Living Products - said the Arizona-based firm is committed to maintaining the building, which it bought in 2005 for about $7 million.
The firm has allocated funds to deal with issues such as wood rot. Eight pieces of wood with rhyming Chinese couplets carved on them in the late 1800s or early 1900s have also been given a fresh coat of paint.
To preserve the oriental setting of the place, furniture with special designs was brought in.
"There is a table in the middle of the sales hall which the antique seller said is from a Chinese palace and has 10 dragons carved into it," said Mr Chang. "The display shelf behind the counter features cranes and bats, which symbolise longevity and happiness, respectively."
Gazetted as a national monument in 1973, the former Thong Chai Medical Institution is laid out like a siheyuan (courtyard home).
He decided to purchase an old building in Singapore and transform it. He wanted to be the custodian of it, and help preserve the heritage and culture of this country.
MR JEFFREY CHANG, of Forever Living Products, on why the firm's founder, Mr Rex Maughan, bought the former medical hall.
According to the National Library Board's website, the building's roof, covering the three main halls, is the only one of its kind here. It features green-glazed tiles. There are traditional Chinese designs along the sides of the roof, depicting branches with leaves and blossoming flowers.
A number of original artefacts remain in the building, as part of an agreement between Forever Living Products and the Preservation of Sites and Monuments, a division under the National Heritage Board. The firm agreed not to sell or remove them.
"For example, the staircase and the wooden doors in these halls are all original. There are also three signboards, one of which is a green one presented by the (Chinese) emperor to the Thong Chai organisation in China," said Mr Chang. The words on the green sign say dong jian xi bei, which he explained refers to the merging of Eastern and Western styles of medicine.
While there are no tours, the building is open to visitors. Mr Chang said fewer than 100 tourists visit each month. "We do encourage people to come in and visit, and appreciate the building," he said.
Built by Chinese immigrants, the former Thong Chai Medical Institution was funded by philanthropist Gan Eng Seng, a labour contractor, together with public donations. The poor went there to receive free medical services.
Thong Chai comes from the Chinese words tong, meaning universal, and ji, which means relief.
In 1976, the medical institution itself moved to a new building in Chin Swee Road. The building at Eu Tong Sen Street was returned to the Government, which restored and renovated it. From 1999 to 2002, the building housed pub-disco Lan Kwai Fong, followed by restaurants Asian and Jing. All went out of business after about a year.
In 2005, it was bought by Forever Living Products, whose founder and president, American businessman Rex Maughan, 79, likes to collect old buildings. Said Mr Chang: "He decided to purchase an old building in Singapore and transform it. He wanted to be the custodian of it, and help preserve the heritage and culture of this country."
Mr Chong Shaw Fong, 69, spent a year working as a traditional Chinese medicine (TCM) physician in the old medical hall. He said in Mandarin: "There used to be four physicians on each shift, all sharing an area about the size of half a basketball court. There was no air-conditioning like today."
He said each physician saw 60 to 80 patients a day, from children to the elderly, who needed help for ailments such as the cough and cold, headaches and rheumatism. The physicians used to prescribe herbs that required boiling and preparation.
Mr Chong, who now runs his own TCM shop in Upper Cross Street, joined the medical institution when he was 27. He had to take an internal examination at the building, held once every three years.
Recalled Mr Chong: "We entered the hall by the front door along Eu Tong Sen Street, and were supposed to exit through the back door (after the exam), to prevent any cheating. But it had been three years since the door was last opened, so the lock was old and rusty and could not be unlocked. Someone had to smash it before we could get out," he said with a laugh.
Despite spending just a year at the building, the place holds fond memories for Mr Chong.
"Because of the small compound, everyone who worked here was almost like family," he said. "We celebrated festivals together. I will always remember that feeling."