Josefina Yamamoto, who was also a consultant working on the series, told the Associated Press that the project was “not an effort to take advantage of the work of others but instead wanted to preserve these rare specimens.”

The rarer a piece of artwork is, the more difficult it is to find it, in this case a 16th century painting of Prince Henry, who was crowned King of the Romans and later adopted the name of Romulus. Until recently only four of the original paintings were known and have not been reproduced.

At least two paintings were sold to British auction houses last year for an eye-watering €19 million, the highest price paid for an example of the Roman era artwork, according to the auction house Christie’s.

The price, said to be in excess of €8 million, helped drive a spike in demand for similar works that were part of an international sale in 2010 at Christie’s in London, where more than 10,000 of the works were sold for €1.5 million ($1.9 million).

Many of the paintings were transferred out of museums because there is a lack of space.

Some were used as canvas for decorative paintings to beautify homes, but others were used by the wealthy to represent luxury items. Some were sold by collectors who hoped to sell them themselves. Others were passed down through family lines, and some were created for private collections.

The prince’s brother, the Austrian-born Prince Felix III of Prussia had inherited one of his paintings as a young prince, from his mother. In 1839 he bought it for a hefty sum and used it as his personal painting for six decades, until his death in 1943.