Matt Williams and Erin Maplesden were lying on the Governor General's manicured lawns.

"I've never seen grass so green," Ms Maplesden said.

The pair had just toured the inside of the building, where antique furniture and Aboriginal art adorns the halls.

"I like how they've kept the heritage feel of it. It's massive as well," Ms Maplesden said.

The grounds stretch forever, 54 hectares, with impeccably kept flower beds and trees shading the home, the stables and even a pool (closed to the public Saturday unfortunately).

Tom Higgs was sitting with his family under a tree and said open days like this were important.

"It makes it mean something to people," he said.

"It reminded me of going to Elvis's place. Elvis had more toys."

Graceland might have motorcycles and horses, but Government House has roos and the 1970 Rolls Royce Phantom VI, a special car made for the Governor General.

Beautifully kept, with crystal glasses sitting in holsters in the passenger cabin; the Rolls has even conveyed the Queen.

Marlene Ball was just about to have a picnic with her family.

She'd last visited ten years ago and said it was great for the public as it gave them an insight into the Governor General's life.

"The drive in is most impressive for overseas visitors," Ms Ball said.

She said she was fascinated by antiques and gardens, with Government House delivering on both fronts.

The residence first saw use as the Governor-General's home in 1927, with the Yarralumla grounds on the edges of Lake Burley Griffin slowly becoming the massive site it is today.

The last addition was the kitchen and service wing in 1993.