42 cm Haubitze M. 14/16
The 42 cm L/15 Küstenhaubitze M. 14 was a superheavy siege howitzer used by Austria-Hungary during World War I and by Nazi Germany during World War II. Wikipedia
Caliber: 420 millimetres (17 in)
Maximum firing range: 14,600 metres (16,000 yd)
Used by: Austria-Hungary; Czechoslovakia; Kingdom of Italy; Nazi Germany; Hungary; Romania