Directions:

This map covers several sites in 2a, plus sites toward the east in the original Old Berlin:
Heilige Geist Kirche, across Spandauer Straße from the former site of Apotheke zum weißen Schwan, where Klaproth joined Valentin Rose, Spandauer Straße 1 - N52 31.26 E13 24.19.
Apotheke zum Bären, beside the Nicolaikirche, where Klaproth did his famous work on zirconium and uranium, north terminus of Probststraße - N52 31.04 E13 24.46.
Märkisches Museum, holding historic displays of Berlin including the wooden city model dating from 1750, Am Kallnischen Park 5 - N52 30.84 E13 24.88.