Well, to be honest I am still trying to figure out the history of that building, as well as of the entire compound on 9 Chongwenmen West Street. The compound is a collection of historical buildings dating from before 1949. See the shot of the old picture of the compound.
The central and most important building is now the office of Ms. Wang Yili, see:
http://www.wangyili.com/yw/yw-sy.htm
Ms. Wang in involved is many organizations, including the China Charity Federation.
I was invited for a lunch along with my friend Peter Ritzen and his wife Stella. Peter found a piano in the dining room and promptly gave us a private concert. Also joined was the Chairman of of Jiamei Dental, Mr. Liu Jia, with whom we work closely.

The building kept its charms from a bygone era. As far as I understand (and might be wrong), another building of the compound that housed the Société Générale de Belgique and the bank (later Fortis) was the location of a Belgian bank before 1949; presumably called Banque Sino-Belge (later renamed to Banque Belge pour l’Etranger). I remember visiting that building in the eighties and looking at old pictures of thee bank before 1949. Checking Google it became more and more confusing as there is little clear information of what was the Belgian diplomatic presence before 1949. Apparently the Belgian Legation quarters were somewhere else close to Saint-Michaels Church, adding to the confusion.
Before 1949 Belgian companies were actually very active in the industry, railways and urban public transport. One company was ACEC, the company I represented in Beijing 1980 to around 1988. A Belgian-French group was involved in building major railway lines in China.