A five-storey observatory on Swansea's seafront has been put on the market.
The city council, which currently owns it, says it is looking for "imaginative" proposals for the future of the building near the marina.
It has been empty since Swansea Astronomical Society moved out two years ago blaming increased rent and other costs.
The council says interested parties need to submit their proposals and financial offers by the end of March.
It has not put a guide price on the building.
The observatory was built in 1988 and includes a domed roof and an access tower that houses a spiral staircase.
It also includes a stained-glass roof by artist David Pearl and panels of carved poetry by Nigel Jenkins.
Coun Gareth Sullivan, Swansea council's cabinet member for regeneration said: "We'd like to see a mixed-use development that incorporates features of the existing observatory building.
"But we'd invite any developers with other imaginative design ideas to get in touch because we don't want to preclude innovative proposals.
He added: "This building presents an exciting opportunity at a prestigious waterfront location within touching distance of the city centre that offers panoramic views of Swansea Bay.
"Bringing the observatory back into use would add even more vitality to the promenade."
The council said it had recently upgraded the promenade between the observatory and Civic Centre with new lighting, handrails, benches and bins.
The astronomical society now uses an observatory at the Fairwood playing fields on Gower.