A Hong Kong charity founded by former Hong Kong chief executive CY Leung has relocated its global headquarters to a century-old historical site that had been built in response to a plague outbreak in the 19th century.

Leung, chairman of GX Foundation, said on Friday the move to No 4 Hospital Road in Mid-Levels is aimed at "inheriting" the philanthropic spirit of the location as it once also served as a dormitory for cleaners and a shelter for the homeless.

"It isn't an ordinary, high-rise, glass, modern office building. It has its character, its history, and is quite prominent in the neighbourhood," he said.

"More importantly, it has the spirit of philanthropy behind it. Mostly it's a result of the work of the contractor who built this building 104 years ago.

"So we'd like to inherit and extend this spirit throughout the work, and hopefully we want you to spread the message to others in Hong Kong, particularly the young students," he said, adding that its first open house event would be held on Sunday.

The foundation, established by Leung seven years ago, is focused on providing humanitarian assistance in countries within the Belt and Road Initiative such as by treating cataracts and fighting dengue fever.

The historical site, built in 1921, is known for its neoclassical style with a stepped layout that conforms to the terrain of Victoria Peak.

The site, with a long association to public health service, covers around 1,047 square meters, with its buildings rated as "Grade II" historic, meaning they are considered as having special merits and shall be "selectively preserved".

It was granted to the foundation by the government in July under a private agreement at a "symbolic land price".

Leung said revitalisation of the site took about four-and-a-half months, during which centralised air-conditioning systems were installed and the buildings' original structure, craftsmanship and features were preserved.

He added that the cost of such revitalisation is not high.

Leung, a vice-chairman of the Chinese People's Political Consultative Conference, also emphasised that the foundation would hold more outreach events at the site.

Foundation chief executive Emily Chan said such events would be held at least twice a year so that the public can learn more about the foundation's work and the history of the building and its impact on the city's public health development.

Since its establishment, the foundation has facilitated more than 25,000 free cataract surgeries in five countries in the world, with its overall initiatives covering 10 countries across four continents.

Looking ahead, Leung said the charity would also look into how to expand its services beyond these countries.