Perth's most famous block of land, which was once home to the mansion dubbed Taj on Swan, has been passed in at auction.

The asking price for the 6,582-square-metre parcel of riverfront land in Peppermint Grove was rumoured to be as high as $30 million, but bids fell way short of that mark.

The grand Taj on Swan sat vacant for many years, before it was demolished in 2016. ( Supplied: Sean Guilbert )

Plenty of curious onlookers gathered at the Bay View Terrace property, which is owned by Indian billionaires Pankaj and Radhika Oswal, but bids were few and far between.

Despite that, realtor Vivian Yap and Auctioneer Mack Hall said there had been lots of interest from prospective buyers both local and abroad.

The auction attracted plenty of onlookers, but not many bids. ( ABC News: Sarah Collard )

"It's one of the more important properties that we have here in Western Australia … certainly one of the biggest blocks in Peppermint Grove and one of the biggest in Perth," Mr Hall said.

The auction asking price began at $20 million, with the starting bid coming in at just half of that before being passed in at $15.6 million.

Auctioneer Mack Hall says the land could be sold in smaller lots, but that is not the desired result. ( ABC News: Sarah Collard )

There are expected to be further negotiations with the highest bidders.

"If that fails to bring about the sale, we will then we will begin to take expressions [of interest] in individual lots, but that is not desired," Mr Hall said.

Pankaj Oswal (2nd right) and his wife Radhika (2nd left) and their daughters 12-year-old Riddhi and 18-year-old Vasundhara leave the Supreme Court of Victoria in 2016. ( AAP: Julian Smith )

The plot gained significant public attention by the Oswal's ambitious but ultimately futile effort to build their $70 million "dream home" on the site.

The partially built mansion was abandoned in 2010 after the couple left the country following the collapse of their ammonia company, Burrup Holdings.

The Taj on Swan, in Perth's exclusive Peppermint Grove, was to include seven domes, a temple, gym, swimming pool and parking for 17 cars. ( AAP Image: Tony McDonough )

The couple owed over $100,000 in unpaid rates to the council and the Australian Tax Office froze the land sale as the couple allegedly owed millions in unpaid taxes.

The unfinished mansion become a haven for squatters, drugs and illicit parties before the dilapidated property was finally demolished in 2016 after a longstanding battle with Peppermint Grove council.

Both cases were settled in 2016.