The interest is sparked by the size of the site, with most of the buildings in a dilapidated state.
"Apart from two buildings, probably the rest is history," she said.
Those buildings include the area of the hall at the left of the main entrance, and some classic woodwork leading to a boardroom upstairs.
A hospital first opened on the site in 1879 and, after being largely rebuilt in the 1960s, it closed in 1999.
Some former staff quarters were used for boarding accommodation for some time, while the main buildings deteriorated through vandalism, before a fire in 2010 led to the site being fenced off and closed to the public.
The site was sold initially to intending developer Jason Dempsey, and then on auction site Trade Me to Mr Bieniowski.
It was used for scenes in a horror movie, Hollow Crossing, and paranormal investigations group Haunted Auckland became interested in the buildings, gaining access to photograph the interiors in 2012.