"There is an answer to the doctor's question. All the Dachaus must remain standing. The Dachaus, the Belsens, the Buchenwald, the Auschwitzes – all of them. They must remain standing because they are a monument to a moment in time when some men decided to turn the Earth into a graveyard. Into it they shoveled all of their reason, their logic, their knowledge, but worst of all, their conscience. And the moment we forget this, the moment we cease to be haunted by its remembrance, then we become the gravediggers. Something to dwell on and to remember, not only in the Twilight Zone but wherever men walk God's Earth."
-Rod Sterling,
The Twilight Zone,
Death's-Head Revisited" (1961).
Eisenhower had his military photographers take detailed photos of those places, and he said that in 50 years, people will forget, and say it never happened. He wanted a photographic memorial.