The image caption said it was a Serbian gun - looks late 19th century but not certain.
Charlie
Hi! May be Schneider-Canet 120mm field howitzer M. 1897
https://www.bulgarianartillery.it/Bulgarian%20Artillery%201/Schneider-Canet%20120mm%201897_Hb%20Serbian.htm
or Schneider-Canet 150mm mortar M. 1897
https://www.bulgarianartillery.it/Bulgarian%20Artillery%201/Schneider-Canet%20150mm%201897_Ms%20Serbian.htm
Thanks.
It seems to be a 120mm Schneider-Canet 1897 howitzer. The Serbian Army bought 24 of these from Schneider and they
were still in use at the start of WW1.
There are 3 survivors - amazing considering how few were in service.
One is rotting away at the Military Museum in Sofia (I think Bulgaria bought some as well)
http://www.passioncompassion1418.com/Canons/Eng_AfficheCanonGET.php?IdCanonAffiche=1343
There are two at a Serbian monument
http://www.passioncompassion1418.com/Canons/Eng_AfficheCanonGET.php?IdCanonAffiche=1342