Sitting at the western edge of Luisenplatz, this gate built by Frederick the Great in 1770 to…read morecommemorate victory in the Seven Years War. It ended up being designed by two architects--Karl von Gontard, who designed the side facing Brandenburg Straße and his student Georg Christian singer, who designed the one facing Luisenplatz, which was the side originally towards the fields, (though the square itself outside the gate was created in 1744).
The gate was built on top of a site that used to be a smaller town gate along a wall surrounding central Potsdam, which controlled the flow of traffic into the city. In 1900 when the city walls were torn down the Brandenburg Tor was left standing.
Again as a landmark not much to do except view it and walk through it, though I can see how considering its location leading towards a main shopping thoroughfare there could be community and seasonal activities set up in its vicinity.