Edinburgh's King's Theatre is to close for two years for a £20m facelift.
Initial designs for the 112-year-old, A-listed building include removing 200 seats, from 1,300 down to 1,100, to provide more hospitality.
A fundraising campaign, launched by actor patron Brian Cox, promised to deliver a modernised, more sustainable theatre by 2023.
In 2012 the theatre had a £2.6m refurbishment including a new roof and a revamped foyer.
The works include removing the back rows of the upper circle to create a roof top hospitality and studio space.
The box office, refitted six years ago, will be replaced with another café bar.
Management argue it makes sense to have fewer better seats in a sustainable, modern theatre able to host more kinds of performances.
They have already secured almost half the funding needed.
Productions will transfer to the Festival Theatre for the duration of building work from 2021 to 2023.
Duncan Hendry, chief executive of Capital Theatres, said: "The King's Theatre holds a special place in the hearts of many people from Edinburgh and further afield.
"The King's really is 'Everyone's Theatre' and throughout this exciting redevelopment project we hope people will help us secure the future of their theatre.
"In early 2019 we will provide ways in which people can engage with, give opinion and support the project."
Donald Wilson, City of Edinburgh Council's culture and communities convener, said: "The King's Theatre has been a firm Edinburgh favourite for over a century and the council is proud to pledge £4m towards its redevelopment.
"From some of the most talented community stage groups in the country and children's shows, to theatre directly from London's West End, the 'Grand Old Lady of Leven Street' has always been Edinburgh's theatre for everyone.
"This essential investment drive will help all of us enjoy a night at the King's for many more years to come."