Melbourne's tallest skyscraper, a 90-storey giant given the nod by Premier Daniel Andrews for Crown Casino last week, will overshadow the Shrine of Remembrance on winter afternoons.

Labor's approval for Crown's $1.75 billion tower comes despite the party pledging it would never allow the Shrine to have new shadows cast over it, because it was "sacred".

Labor attacked the now Opposition Leader Matthew Guy in 2014 for approving a lower tower that also casts a shadow on the Shrine during winter afternoons.

Mr Andrews and Planning Minister Richard Wynne last week said they had sealed a deal with Crown behind closed doors to approve the tower – despite it also breaking new density rules set by Labor for city skyscrapers.