The owners of rare books, including those by Galileo and Sir Isaac Newton, have described their "profound joy" at having them returned.
The books, worth £2.5 million, were taken from a warehouse in Feltham, west London, during a "highly sophisticated burglary" almost four years ago.
Two members of an organised crime group abseiled from the roof to break in and steal the books.
The books were then transported to Romania by the criminal gang.
In October, 12 men were jailed for a series of burglaries.
Kingston Crown Court heard that among their raids was the "deliberate targeting" of customs clearing centre Frontier Forwarding in Feltham.
Works of "immense cultural significance" which were due to be shipped to the US for a specialist book auction were at the site.
The hoard included rare versions of Dante and sketches by the Spanish painter Francisco de Goya, as well as the titles by Galileo and Isaac Newton dating back to the 16th and 17th Centuries.
They belonged to three book dealers, two Italian and one German, and the books were later found buried under a house in rural Romania.
All but four of the 240 books have been recovered after detectives from the Met Police travelled to Bucharest following an investigation with authorities in Romania and Italy.
Eighty three books recovered suffered some damage, ranging from slight to severe. This mainly consisted of damage from water and mould due to how the books had been hidden underground, and broken spines believed to be from poor methods of transportation.
Twenty-eight were assessed as having substantial damage and two books were so severely damaged they have been initially assessed as being beyond repair.
One of the victims Alessandro Riquier, from Italy, said: "After three-and-a-half years, finally this terrible story has a very happy ending.
"I went to Bucharest full of hope but also a little bit scared about the damaged books. I was very excited and it was a great joy to handle my books again."
Another book owner, Natalina Bado, also from Italy, said: "The experience of returning the books was very positive and exciting. Reviewing and touching our books three years and nine months after the theft was a profound joy.
"Every time we were about to view a book we had many expectations regarding the conditions and when we found our works in good condition it was a great happiness for us, just as it was a deep pain to see some damaged books."
Det Insp Andy Durham, who led the investigation, added: "It was lovely to see the joy of each victim being reunited with these irreplaceable books."