White Night lights up Melbourne's CBD

Throngs of partygoers have flocked into Melbourne's CBD for the annual White Night spectacular.

Federation Square is being draped in a 'liquid sky' as neon dogs frolic atop the State Library and snow covers Little Bourke Street for the all-night event, which began at 7pm on Saturday.

Artistic Director David Atkins said the event, which last year drew a crowd of about 600,000, would "shock the senses".

Key city roads have been shut down and crowds are encouraged to use public transport to get to and from the event.

White Night will run until 7am Sunday, with a highly visible police presence.