Crowds flock to see the gigantic wine barrel at Heidelberg Castle . Four such vats were made between 1591 and 1751, but only the last can still be seen. Following a visit to Heidelberg, Anton Praetorius, a German theologian and opponent of witch hunts, praised one of the four barrels. The oldest was known as the Johann Casimir barrel and it could hold 127,000 litres of wine.