Nice piece, graffiti in the field.
Obverse: cross with superimposed city coat of arms, legend in the rim:
COIN.NOVA.REIPVB:FRANCOFVRTENSIS::;
Reverse: imperial eagle, surrounded by legend:
FERDINAND-II-D:G:ROM.IMP-SEMP.AVGVST:1634:AE;
Silver, diameter 44 mm, weight 28.8 g.