What area in Gauteng South Africa has the zip code 20011?

Johannesburg Postal CodeThe postal codes of South Africa are not similar to the zip codes of the United States. South African postal codes are four digits long, each representing a particular post office or suburban area.

The code 20011 does however seem very similar to the Johannesburg code 2001. This code represents the inner city of Johannesburg, most likely Braamfontein or Newtown. It is a street address. The major code for Johannesburg (i.e. its central post office code) is 2000.
90210