Architect Glenn Harper is one of the few public admirers of Sydney's off-maligned concrete heritage.

Sadly for Mr Harper, his favourite example of Brutalism in Sydney, the "bold and heroic" building formerly known as the Bidura Children's Court is under threat of demolition.

UTS Building 15 in Ultimo is an example of Sydney's Brutalist architecture Credit:Jessica Hromas

The children's court, the only in-situ cast concrete courthouse built in Sydney, is one stop on an audio tour of the city's best Brutalist landmarks launched at the Sydney Architecture Festival on Saturday.

"It has suffered from neglect, so when you do look at it it looks a bit depressing, but you need to look past that," Mr Harper said. "It was built and designed with so much love and care."