Notes from the HKU website:
Hung Hing Ying Building sits squarely in front of the Main Building and characterised by a central dome. Its red brick façade matches that of the Main Building's.
This Edwardian-style building was originally designed to house the University Union. It was opened in 1919 with the support of Sir Catchick Paul Chater and Professor G P Jordan, who was the then Acting Vice-Chancellor of the University.
After World War II, the Building was temporarily used for administrative purposes. In 1974, it was converted into the Senior Common Room for University's senior staff.
In 1986, the Building was named in honour of Hung Hing Ying, in recognition of his support of the University. In 1995, Hung Hing Ying Building was declared a monument by the Hong Kong Government.