The obverse is the city of Frankfurt from the west toward the bridge over the River Main. The sun radiates on the horizon as a sail boat & rowboat cross the river Main. The denomination of 3½ (South German) gulden equaled 2 (North German) thalers. The thaler equivalent was stated on the coin to facilitate commerce with northern Germany.
Script: Latin, FREIE STADT FRANKFURT, ZOLLMANN translates to Free City of Frankfurt
Engraver: Christian Zollmann