Frankfurt am Main - Niederrad :
Where: Parking on Mörfelder Landstrasse 360, 60528 Frankfurt – Niederrad near Stadionbad, (not sure this isn’t the parking for the Stadionbad)
Map: https://maps.app.goo.gl/y1yCpyRcuXWDjD1w8
Public Transport: Take Tram 21 to Frankfurt Stadion, then walk for approx 4 Mins south along Mörfelder Landstrasse, you will find the parking on your right hand side.