Today at roughly the same spot (except there are no observation platforms I can climb up on to see over the Wall). It's still a vacant lot; the museum was never built and the basement interrogation room were reburied to preserve them. Instead Niederkirchnerstrasse is a regular street now. This section of Wall is one of only 3 left in the city.
I found it ironic that in 1988 I chose to go to one of the spots that a few years later would be designated as a historic preservation site for the Berlin Wall.