So, after much discussion with my Dad and looking at the other slides in the same processing batch, we’ve determined that the subject of 1964 is Itatiaia* National Park near Resende, Brazil.
I searched around for an image of Itatiaia that resembled Grandpa Leo’s vantage point when he shot his slide in 1964. I found this image on skyscrapercity.com – a contemporary view that looks very much like what Grandpa was looking at so long ago:
And here is the scanned image of Grandpa’s slide. I’d say its a match! What a beautiful place.
From what I’ve read, the park has rainforest and mountains. I came across many images of stunning birds – it seems there is a well-known bird watching tour through the area.
For my fellow map junkies, here is a map of the park & surrounding area: