Prime pieces of property in Perth's most sought-after suburbs that have been waiting months or even years for buyers may finally be snapped up as the local real estate market shows signs of stabilisation.

Australia's most famous "superblock" is set to go under the hammer next month and expressions of interest in another famous address, the former site of socialite Rose Porteous' mansion Prix D'Amour, are closing this week.

In the March quarter, Perth's media house price had its lowest rate of annual decline in more than 18 months, according to Domain Group data.

The empty 6582-square-metre superblock landholding, at 2 Bayview Terrace, Peppermint Grove, once destined to be home to a $70 million Perth palace for Pankaj and Radhika Oswal with six bedrooms, a temple and parking for 17 cars, has been on the market since October.

The sprawling site sat incomplete since the couple left Australia in 2010 when the ANZ bank called in more than $US500 million ($648 million) in loans and appointed receivers to their Burrup fertilisers business.

The site, which is being marketed by Vivien Yap, of LJ Hooker Claremont, and William Porteous, of William Porteous Properties International, could see it either sell via auction conditions as a one super lot or purchased via individual parcels.

Mrs Yap said the uniqueness of the site was behind the decision to take the property to auction.

"The vendors amalgamated the site to a size that you seldom see this close to the city, let alone with the surrounding amenity and residential values," she said.

"It's near impossible to put a price on such a rare offering, so the vendors have opted for an auction to allow the market to decide what the site is worth."

In February, selling agents announced a plan to split the block into six lots.

Mrs Yap said the auction, to be held on Saturday, May 27, could be held in two ways.

"Firstly, we will open bidding for the entire site; that will allow either single buyers or a syndicate of buyers to come forward," she said.

"A single buyer may want the site for an iconic residential vision or a syndicate may wish to subdivide. Now that the former incomplete residence has been removed, the site presents an extraordinary blank canvas.

"If the sale of the site in its entirety does not eventuate, we'll invite bidding for individual allotments on the site ranging in size from 1000 to 1151 square metres. This offering is unique in itself as most of the parcels throughout Peppermint Grove are around 1500 square metres in size: this is a boutique opportunity."

In Mosman Park, a palatial house at another famous address is on the market with an asking price of about $15.25 million.

The house that replaced Rose Porteous' Prix D'Amour at 149 Wellington Street has sprawling views of the Swan River, a glass domed elevator, underground gym, marble flooring, seven bedrooms and a four-car garage.

It is also being sold by Mrs Yap, with colleague John Hunter, of LJ Hooker Dalkeith and Claremont, with offers closing on Wednesday.

Owners John and Lilian Clinton, who purchased the lot in 2008, are selling because they have relocated to Los Angeles.

According to Domain data, the owners have been trying to sell the home since March 2015 via expressions of interest and later, an initial asking price of $18 million.

Mr Hunter said the home, which is set across a 1610-square-metre double block, was custom built by Zorzi Builders in 2010.

"It's absolutely one of a kind in every aspect. You don't have any other properties in that location that actually are on two blocks," he said.

"So it's an amazing location and the views are just phenomenal. You actually have a north orientation solar aspect while still having a river view. But the house itself is very grand.

"It's over the top and really amazing."

Described in its Domain listing as "Gatsby-esque", the three-level art deco-style house boasts seven bathrooms, an underground wood-panelled cellar, a towering foyer with a glass chandelier, a horseshoe driveway, an alfresco area with a pizza oven and staff or guest quarters.

The state-of-the-art kitchen overlooks the pool and the Swan River.

Mr Hunter said the layout of the home suited a family, in particular a multi-generational family because of the lift that accesses three levels.

Other features include smart systems, a Sonos entertainment system and remote-controlled curtains, lighting and front security gates.

Mr Hunter and Mrs Yap have estimated the replacement cost of the home would be more than $20 million. Mr Hunter said there had been strong interest from overseas buyers looking to relocate to Australia.

Across the river, 30 Jutland Parade, Dalkeith, has been on the market since November 2015. The character home, with panoramic river views, was first listed for sale by Anderson Davies Real Estate for $5 million and has now been reduced to $4.7 million.

The other superblock: Denby Roberts' Mosman Park land has been on the market for more than four years. Photo: Supplied

Another "superblock," at the corner of Hill Terrace and Johnson Parade in Mosman Park, also remains on the market since it was first listed in 2012.

The 3664-square-metre landholding is adjacent to the Swan River and is owned by Denby Roberts, the only daughter of the late Multiplex founder John Roberts.

Selling agent William Porteous, of William Porteous Properties International, said he was open to offers.

"But the offer has to be around $30 million and at the moment no one is going to pay that," he said.