I edited the wikidata on the basis of these texts https://monument.heritage.brussels/nl/Brussel_Vijfhoek/Troonplein/1/30617 and https://www.brainbuildings.be/blogs/axa-belgium-een-slim-gebouw-voor-een-nieuwe-werkmentaliteit They clearly says expansion in the 1962-1965 and renovated to it's current look in the 2010s