This weekend, more than 105 buildings across Melbourne will be unlocked for your snooping pleasure. From private homes and underground substations, to creative office spaces and cutting-edge architectural achievements, Melbourne is opening up.

There is one space, however, that draws the most debate, controversy and intrigue. It is the most hidden site of all, yet sits above one of Melbourne’s most traversed.

It’s the Flinders Street Station Ballroom. It was largely abandoned in the early 1970s, although used for a time as a theatrette in the late 1980s.

Only 20 people will be allowed to visit the ballroom this weekend: and we’re giving away three double passes.

As our writer Nick Acquroff described it during a visit in 2013, when it was opened to the public for the first time: “It’s an intensely beautiful space, punctuated by that lingering sense of time and isolation.”

The space remained a part of the Victorian Railways Institute until the mid 1980s, when railway employees used it after work hours. We’ve also been told boxing matches were sometimes held there on weekends.

In February of this year, it was reported that the station would receive a $100 million facelift, which would include restoration of the ballroom.

The ballroom is a rarely seen icon of the city, and to be one of the lucky few inside is certainly a story to tell.

To enter, email us at win@broadsheet.com.au with 'Flinders Street Ballroom' in the subject line. The winners will be contacted on Wednesday evening.

Open House Melbourne Weekend runs from July 25 to 26 at various locations around Melbourne. For the full program, visit openhousemelbourne.org.

This competition is now closed.