Castle Rushen will re-open to the public on Saturday after extensive refurbishment works.
Concerns had been raised as to why the heritage attraction hadn't reopened alongside other attractions earlier this year.
Manx National Heritage says it's due to the first major improvements to the public facilities since it took the site over 30 years ago.
In a statement MNH says: "The works have seen the construction of a new fully accessible bridge to the Keep, level access to the ground floor rooms, new glazed doorways in the Gatehouse, a new shop area and an interpretation room.
"Castles are designed to keep people out but the new improvements will welcome visitors and have been undertaken to give the widest possible access – including those with limited mobility.
"This conservation project began at the close of the season in 2017 and has taken place during a relentless winter.
"Our visitor's safety is paramount and we take this opportunity to thank our supporters for their patience whilst these key works have been under way and apologise for any inconvenience it may have caused.
"Visitors will still see scaffolding as our contractors are still working on the roof of the Flag Tower – the very highest point of the Castle and the most difficult to access."