The hoard of classic vehicles, believed to be worth millions of euros, belonged to Dordrecht businessman Ad Palmen, 82, who started collecting the cars 40 years ago, according to auction organizers.

Due to Palmen's reported ailing health, he could no longer keep the vehicles and they were recently purchased by Gallery Aaldering, a motor vehicle dealer run by Nico and Nick Aaldering, for an undisclosed amount.

"The Palmen Barnfind Collection" will go under the hammer in the Netherlands from May 19 as part of an auction organized by Gallery Aaldering and Classic Car Auctions.

"This barnfind collection is truly a unique opportunity for car enthusiasts and collectors around the world to expand their collection," said Nico and Nick Aaldering in a press release.

"We are very pleased to be able to auction these cars through Classic Car Auctions and look forward to seeing how much interest there is in this wonderful collection."

Carlo Te Lintelo, Gallery Aaderling's head of marketing, told CNN on Friday that Palmen's trove, which includes a white Mercedes 300 S convertible, a blue Ferrari 365 and a modest Alfa Romeo Spider, was a closely guarded secret until a fire broke out at his largest warehouse last year. A quick response from the fire brigade prevented the cars going up in smoke.

It is believed that Palmen has a deep appreciation for cars rather than a fondness for specific brands. Many of the models, including Maseratis, Jaguars, Aston Martins, BMWs and Facel Vegas, are in pristine condition, Te Lintelo said.

"These cars are in a great condition and immensely diverse. What you often see is people focusing on one brand when they are collecting cars like Mercedes Benz, Jaguar or BMW. Mr Palmen didn't collect just expensive or exclusive cars he bought everything he thought was beautiful," Te Lintelo said.

He added: "This collection includes cars that are very special. Like the Lancia B4 Spider America. Just to give you an idea, that car alone will sell for €600,000 to €700,000 ($660,000 to $770,000). They are very rare, only a couple of them were made. If in perfect condition, they can sell for up to €1 million ($1.1 million)."

'Cars were his life'

According to Te Lintelo, there remains many unanswered questions about the collection because Palmen is too ill to tell his story.

"We have hundreds of questions about why he started collecting," Te Lintelo said. "So much mystery around the cars because he can't answer. [It's] very sad."

But there is one thing that Te Lintelo believes to be true: Cars were Palmen's passion.

"He was living in the warehouse and not in a luxurious way. Cars were his life," he said. "We want to respect his legacy. This was his entire life. The Gallery Aldering brought the cars but we chose to name the collection after him to honor him."