is older slightly better?

I had a conversation with a client yesterday in which I made the very unoriginal claim that older institutional buildings--say built in the 19th century or early 20th century--outlast buildings from the post-war period (i.e. the modernist stuff that towers of ilium complains about so frequently). I have no comprehensive statistics to back up this claim, but from what I've observed at school campuses, efforts to preserve and continuously renovate old structures are made more readily than decisions to demolish younger stuff.

Scale and context is important, but I'm staking my claim on the proposition that older buildings have robust geometry and materials that outperform the steel and concrete atrocities of the 50's, 60's and 70's.