I have an interesting story relating to your question.

I recently visited Tuzigoot National Monument in Arizona, which, for those who are unaware, is a preserved bunch of dwellings that had been built by indigenous populations many hundreds of years ago. It's now maintained by the National Park Service.

In reading the info placards at the site, in the early to middle part of the twentieth century, the NPS's strategy was to try to restore sites to what they once were--using modern materials, consulting pictures or descriptions of what something used to look like, etc. However, that strategy is no longer current with modern thinking. Instead, the NPS now tries to preserve sites solely to prevent them from degrading, but interferes with the sites as little as possible otherwise. So they may build some drainage to prevent water from destroying something, but they're not going to restore something to what it used to look like. This new way of thinking is apparently the modern norm.