Mary Ann Street Park is a small green space tucked away in the inner-city suburb of Ultimo. The area once lay on the grounds of Ultimo House, which was one of Sydney's grand residences and is pictured below. When it was demolished in 1932 to make way for expansion of the Sydney Technical College (now the Ultimo campus of TAFE NSW), it was believed to be the oldest standing house in Sydney.
Today, the park sits across the street from the TAFE campus. It is also one of the parks in the City of Sydney which allow dogs to roam off-leash.
Be careful when retrieving the cache, as muggles are often nearby. Please also replace the cache securely to make sure it doesn't leave its spot.