martl

i do own a couple of girardengos (4, if memory serves) - in fact, 2 of the examples on the website mentioned by juvela ended up in my garage.

I agree, for exact dating pictures would be necessary. Information about that brand is a bit hard to get, somewhat surprisingly, as it seems to have been quite big at some point.
When doing a web search you may come across the information that they were built by inmates of the Allesandria jail - according to what i could find, this happened quite late (around the late 60ies) and it is unsure whether racing bikes ever were a part of that deal - Girardengo, like Bianchi, Atala or Legnano, built bikes of all kinds.

Also be aware that some Girardengos were made for/under label of RIH (Radsport Hamedl) in Vienna, Austria - which is not connected to RIH/Netherlands. As i said, it's a bit confusing...