The Emporium Development is located on the site of the Myer Lonsdale Street Store, Melbourne. The site, along with the Bourke Street Store, is included on the Victorian Heritage Register (H2100) for its historical and architectural significance within the history of retailing in Victoria and for its social significance within the Melbourne psyche.

As heritage architects, Trethowan provided guidance on the retention of those aspects of the site deemed to have heritage significance and the conservation of the retained building facades at 275-321 Lonsdale Street through to 290-316 Little Bourke Street. The role included implementation of the statutory permit process, detail documentation of the façade restoration works including installation of new shopfronts, and advice to the project architects in relation to new interventions into the facades and preparation of paint and external finishes analyses.

Works involved the reinstatement and reconstruction of missing external details, including masonry elements. Further involvement has delivered proposals for a number of interpretation panels that utilise salvaged internal fixtures and fittings that were incorporated into the internal fit out of the Emporium shopping complex as seen today.