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Mega Lot Exclusive: Three Mosman streets earmarked for 11-storey block of 155 apartments.

Published On: October 14, 2026
Images of homes that may be destroyed for a mega lot

Exclusive: Mosman’s next Mega-Lot swaps 11 homes for 155 apartments.

By ANNA USHER

Eleven Mosman properties have been earmarked for a 42-metre-high apartment block, after NSW Planning Minister Paul Scully declared the site State Significant Development.

The order, signed on September 28, confirms that 1 Countess St, 13, 15, 17 and 19 Earl St and 2, 4, 6, 6a, plus 1/8 and 2/8 Rosebery St can be amalgamated into a 3,900sqm super site with the state government – not Mosman Council – approving future development.

Arial view of mega lot

Eleven properties across three Mosman streets (Earl, Countess and Rosebery) could be demolished to make way for 155 apartments. Google Images.

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A briefing record published by the Housing Delivery Authority (HDA) states the proposed development of the land parcel is an 11-storey residential building comprising 155 dwellings, with 10% dedicated to affordable housing.

The applicant is Mondo Developments, the company behind another plan for 110 apartments on Raglan and Muston streets, first revealed by Mosman Collective last month.

This latest project proposes building 42 metres high on land where the limit is 22 metres, and the HDA says it will need rezoning.

“A merit assessment may result in development standards and dwelling yield lower than proposed in this EOI application,” the record of briefing states.

1 Countess St, Mosman.

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Mondo has offered 10 per cent of the extra floor space as affordable housing in perpetuity, and the authority said the Department expected “value returned to the community from the significant uplift achieved above existing planning controls”.

Company records show Mondo Developments was registered with ASIC on February 26 this year.

This publication found no published records of a combined sale of the site, with all properties individually owned. Six of the homes were marketed in May last year, when CBRE offered 2 to 8 Rosebery St as a 1,758.5-square-metre corner site tipped to fetch as much as $40 million, Mosman Collective reported at the time.

19 Earl St, Mosman.

Lang St plan knocked back.

Meanwhile, the same HDA meeting refused to back a 16-storey block of 128 apartments at 1, 3, 5, 5A, 7A, 7B and 7C Lang St, a neighbouring site put forward by Mackenzie Architects International Pty Ltd.

The Lang St proposal offered 15 per cent of its apartments as affordable housing in perpetuity and needed a rezoning.

“This is inconsistent with local scale and context,” Planning Department Secretary Kiersten Fishburn said.

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