Sixteen months after the last public housing resident was forced from the Sirius building at The Rocks, the high-rise apartment block remains empty while the NSW government determines its fate.

The future of the Sirius has been uncertain since the final tenant, Myra Demetriou, moved out in January 2018 – four years after the government signalled its intention to sell the harbourside site.

The Sirius building has been up for sale throughout 2018 and 2019. Credit:James Brickwood

The delay has frustrated the NSW Opposition, independent Sydney MP Alex Greenwich and the City of Sydney lord mayor Clover Moore, who said it was "unacceptable" the building remained empty.

"With a housing affordability crisis, homelessness increasing and a social housing wait-list of 60,000, it is unacceptable that a building purpose-built for social housing has sat empty for over 16 months," a spokeswoman for Cr Moore said.