TRANSFORMING The Lawn complex into a first-class tourist attraction is something the city council admits it cannot afford.
The site of the former asylum in Union Road, Lincoln, is to be sold amid rising maintenance and running costs.
Included in the sale are the Sir Joseph Banks Conservatory – named after the eighteenth-century Lincolnshire botanist – shops, offices, café units and some parking spaces.
The west lawn will be kept by the council but the future of the south lawn, also a public space, is to be decided.
People who run businesses at The Lawn and visitors are worried about the future of the complex if it becomes privately owned.
But Ric Metcalfe, Labour leader of the City of Lincoln Council, said the basis of the sale is not just the price.
"We are keen to protect the most- used public open spaces surrounding The Lawn, namely the west lawn and the recently refurbished play area," he said.
"This area, as well as much public car parking, will remain in council ownership.
"When we carry out the tender process, it will be in the best interests of the people of Lincoln and we will not base our decision to sell on price alone.
"Any sale will be subject to the leases of existing tenants who currently occupy premises at The Lawn.
"All the council's tenants at The Lawn complex have been notified.
"As required by law, we consulted widely on the sale of the south lawn, which is open public space, and members of the public had until September 15 to comment or object.
"We received no comments or objections and took the decision to sell this piece of land along with the buildings. With the exception of the south lawn, there is no legal obligation for a council to consult on a sale of its own premises.
"We haven't started marketing The Lawn yet, as we are in the process of putting together the sale package to include all legal, property, planning and financial matters."
More than 1,200 people have signed a petition to keep the complex, apart from the main building, in public hands.
"We know The Lawn needs investment, but that does not have to be at the cost of small businesses that operate here," said Stephen Smith, 39, who runs Sanctuary Café.
Visitor Dahlia McIntosh, 36, a mum-of-two from Alexandra Terrace, Lincoln, said the conservatory was one of Lincoln's heritage highlights and needs protecting.
"We live in a typical city property with a small outside space and we use this as our garden," she said.
"I'm not surprised they're going to sell it given how neglected it's become.
"I hope it will remain open and have some money spent on it."
Leader of the Conservatives Darren Grice said his administration's intention had been to re-invest £250,000 of the sale proceeds into creating a world-class tourist attraction.
A further £250,000 would be ring-fenced to meet future running costs until the site became self-sufficient.
"We are not against letting go of some assets, but it's a question of doing it well and engaging with the community," said Councillor Grice.
Victoria Whitworth, head of science at St Mary's Preparatory School, said she would like to see a sale clause to guarantee the conservatory remains open and has money spent on it.
"This is one of the few places in Lincoln that are free and it's a great place for families," she said.
"We also bring children from school here to tie in with topics, including a project about Australia."
Lincoln MP Karl McCartney said: "My worry is they are selling off more than they need to."