A sidenote: literal augments (буквенные наращения) are not used with the Ordinal Numerals when they mean dates: в 1997 году, на 3 сентября.
But even if 1997 were not a date, correct form would be "в 1997-м"
The sentence is presented as a stand-alone, out of context. If you use "a monument", it means there's been no previous mention of the monument, the monument is the 'new information', and as such, the new information is likely to come at the end of the Russian sentence.
Памятник (был) поставлен в 1997 году. (Когда (был) поставлен памятник?) The monument was erected in 1997. (We already know there is a monument, the new information is the date it was erected.)
В 1997 году (был) поставлен памятник. (Что случилось в 1997 году?) A monument was erected in 1997. (Something happened in 1997. What happened? A monument was erected - that's the new information.)