De la part de Adi V

I believe these two guns to be Krupp 150mm siege gun Model 1880, but I'm not 100% positive. A definitive ID would be welcome.
They are emplaced in Roses Park, Drobeta-Turnu Severin, Mehedinti county, at the monument comemorating WW1 fallen, built in 1930-33.
These guns are not known to have been in service with the Romanian army, and are the only ones of this type in the country.
 
There is small inscription on the left hand side of the carriage, below the barrel attachment point, which reads
 
Fried. Krupp
ESSEN o/R No 21
 
The other gun has No 23
 
There's also a barely visible inscription just above the breech, only the number 22 is readable - on both guns