The glasshouse at Wentworth Castle Gardens near Barnsley was dismantled and sent for renovation and repair.
Now parts of 4,000-piece frame are being reassembled as the latest stage of the Â£3.7m restoration project.
The Grade II listed structure, built by Thomas Wentworth in 1885, is due to reopen to visitors in the autumn.
The frame had been dismantled, labelled, cleaned and re-cast where necessary, managers at the castle said.
The plight of the conservatory, which had fallen into disrepair, came to national prominence in the BBC 2 Restoration programme in 2003.
Claire Herring, a director of the Wentworth Castle Trust, said: "We are delighted the conservatory is returning to our site after its sympathetic restoration.
"We are all very excited about seeing this part of Barnsley's heritage restored to its former glory.
"We'll be welcoming visitors from autumn."
Wentworth Castle Gardens said the glasshouse had received funding from a European Regional Development Fund, as well as cash raised by volunteers.
The Wentworth Estate has spent more than Â£17m on the 500-acre site since renovation work began in 2004.
It has renovated areas from gardens, parkland and woodland through to the Grade I listed circular outbuilding called the Rotunda.
The iron frame of a Victorian conservatory has been returned to a South Yorkshire stately home after months of renovation work.