Two new hospital blocks could be built in Birmingham as part of a multi-million pound project.
Birmingham Children's Hospital in the city centre and Birmingham Women's Hospital in Edgbaston are "well beyond their operational life", bosses said.
The £442m plan would see two new blocks built on the same sites by 2025, subject to funding approval.
Parts of the children's hospital are more than 120 years old and the women's hospital is more than 50 years old.
David Melbourne, acting chief executive of Birmingham Women's and Children's NHS Foundation Trust, which is behind the plans, said doing nothing was not an option.
'Crumbling and cramped'
"Our teams have done a great job in recent years with a make-do-and-mend approach, but the cost of that in terms of annual maintenance is growing and is not sustainable," he said.
"These buildings are well past their natural life and are not suitable to providing the spaces and facilities we need for modern care."
A former dental hospital building at the children's hospital and the Norton Court block at the women's hospital are expected to be demolished to make way for the new structures.
It is hoped the project will be paid for with national funding, fundraising through the trust's charity, and money generated from the sale of vacated land at the children's hospital's Steelhouse Lane site.
Professor Sir Bruce Keogh, trust chairman, and former national medical director for the NHS, said the wards and infrastructure at the children's hospital were "crumbling and cramped".
He added the women's hospital site was "struggling to function at 30% above the capacity for which it was designed 60 years ago".
Revamping the existing buildings "to a basic operationally sound and acceptable level" would cost more than £760m, the trust said, with extra investment needed to increase clinical space to meet government guidance.