Newspapers are a wonderful resource for understanding the context and debates around your monument. They include first-hand accounts, updates over time, and public opinion. A newspaper reporter may be standing right there at the ribbon cutting ceremony, describing the event. A community member may have sent a letter to the editor. A series of newspaper articles covering the creation, installation,and reception over time will give you a sense of the "life" of the monument.
Depending on the country of your monument, or its place in time, newspapers may be easier or more complicated to access and use. OCR, or Optical Character Recognition, is used to translate newsprint into readable, searchable text. However, the quality of the print, the orthography, spelling, and other characteristics of the texts may make them difficult to search. Please do ask for help!!
The following is only a brief list of the newspapers indexes available.
There is a wide range of sources for public opinion, from newspaper op-ed pieces, to popular magazine articles, polls, etc.
I distinguish popular magazines from scholarly journal articles on the basis of authority and objectivity. Scholarly articles, peer-reviewed journals in particular, require a formality of documentation and evidence very different from a popular magazine article. For that reason, popular magazines may provide insight into public opinion.
This list of possibilities is just a beginning!