I don't know if one can visit the museum, because it was closed when I walked past. There were no signs to give more information. But it is a beautiful little gem

There are more than a dozen European style buildings scattered throughout Beihai that date back to the late 1800's / early 1900's - refer to the Beihai government web-site (beihai.gov.cn) The site of the ex-British consulate (near the corner of Beijing Lu and Beibuwan Zhong Lu) is open to the public with interpretive signage in CN/EN as is the German Shenbao Foreign Firm Building (a trade organisation established by Germans). All are worth a visit if you are in Beihai for a while (even if many of them are not open to the public). The interpretive signage makes an interesting read of the history of Beihai and its role as a trading port.