A carefree night out. A split-second decision. Young lives tragically changed forever.

Today we’re taking you back to those golden years of the 1980s – when hair was big, clothes were loud, and power ballads were super-charged with emotion.

Sydney was no place for an unwed, pregnant young woman in the early 1900s, but 18-year-old Mary Hutchison had nowhere else to go.

When it officially opened on Sunday, 28 March 1954, "Greenway" was Australia's largest communal social housing complex.

Mosman teenager Alma Plaister was never absent from school. But on Monday 18 July 1932, the brilliant and popular 13-year-old was missing from morning roll call at North Sydney Girls High.

On the busy corner of Ourimbah and Spit Rd, a commercial building known as Island Centre opened to fascinated locals in July 1968.

“When we were waist-deep in the surf, they opened up a murderous fire,” Sister Vivien Bullwinkle recalled after the Bangka Island Massacre of WWII, "mowing us down like a scene I saw in a film as a child.”

In our new series, Mosman Collective unlocks historic local crime case files, revealing new images and details of the lower north shore’s most shocking stories.

On 21 November 1934, Coles came to Mosman, opening the doors of 22 Spit Rd at 9:30am. Goods on sale included seven-piece fruit sets, toys, cotton reels, ladies’ aprons, hats dresses and nickel torches.

Described as “an old colonial home”, Victoria Cottage on Clanalpine St was marketed with stunning views, a formal garden, extensive library, and a swimming pool by local agent James S. Lindsay in August 1986.

Not even Mosman was spared during Australia’s deepest post-war recession in the early 1980s.

Australian competitions aren’t limited to just sport and spelling bees. From yabby races to bed making, prawn peeling to whip cracking, we love nothing more than a good-humoured match-up.

Kids of the 80s and ’90s will remember family dinners at Sizzler, the iconic chain famous for its all-you-can-eat salad bar, unlimited ice cream and complimentary cheese toast.

It has been 100 years since children’s author May Gibbs brought the ocean to life in a book featuring an underwater creature called Little Obelia.

Lower north shore locations and identities with stories to celebrate have a chance to become recognised with the universally known heritage symbol – a blue plaque.

“Welcome to Paradise” was the line agent Rob Simeon used when marketing the Golden Triangle property known as “Heachem”, in 1999.