A Georgian revival-style building at 12 Collins Street and five-level office space next door at number 14-16 (near Spring Street) were expected to fetch about $35 million in total, agents estimate.

The properties known as Victor Horsley Chambers and Chanonry have been classified by the National Trust along with several other notable neighbouring buildings under its Alcaston House Group listing.

Neither property has been traded since 1971 when they were brought by the same Toorak family for a combined $1.2 million.

The so-called Paris end of Collins Street is one of Melbourne's most tightly held areas where no building (under $100 million) has been sold between Swanston and Spring streets in the past eight years.

The properties were expected to attract strong local and offshore interest given the market's strength and the scarcity of similar available buildings, Savills' agents Clinton Baxter and Nick Peden said.

They were fully let to retail and office tenants with leases that included a six-month termination clause allowing potential buyers to reposition, owner-occupy or redevelopment them, Mr Baxter said.

Earlier this year a local investor paid $28.25 million for the Melbourne headquarters of China Construction Bank, a B-grade office building at 410 Collins Street.

Close by, on the corner of William Street an Asian investor snapped up a partly vacant building at 446 Collins Street for about $34 million.