Former President Jimmy Carter is celebrating his 85th birthday with the reopening of his presidential library in Atlanta.

The museum opens its doors again Thursday after a $10 million overhaul. It now devotes more space than any other presidential library to a commander-in-chief's time spent after the White House.

About a third of the Atlanta museum explores the Georgia Democrat's life after he was defeated in 1980 by Ronald Reagan.

Carter says he wants visitors to "get an insight on what a former president might do when they're involuntarily retired from the White House four years before they anticipated."

It's the first major update to the museum since it was built 23 years ago.

Tags: Atlanta, Jimmy Carter, 85th Birthday, Carter Center