Big Bertha was actually a different gun. That was the monster howitzer used to pound the fortress of Liege in 1914.
I don’t think that Paris Gun was ever found. They dismantled it.
Per Wiki:
https://en.wikipedia.org/wiki/Paris_Gun
“...The gun was taken back to Germany in August 1918 as Allied advances threatened its security. No guns were ever captured by the Allies. It is believed that near the end of the war they were completely destroyed by the Germans. One spare mounting was captured by American troops in Bruyères-sur-Fère, near Château-Thierry, but the gun was never found; the construction plans seem to have been destroyed as well.[10]..”
Thanks.