Hans Christian Andersen and Jules Verne, the Russian Czar, Ludwig II King of Bavaria, they all visited the Paris world exhibition in 1867. A major attraction was an ingot of the recently discovered heavy metal Indium weighing 500 grams. What nobody knew, this ingot dyed indigoblue was a fake made from lead. The real indium was carried around by its discoverer Hieronimus Theodor Richter, a professor specialising in the analysis of minerals using a blowpipe at the Mining Academy in Freiberg, tucked into the leg of his boot. He only showed it to his specialist colleagues in private.

A flash of inspiration in his sleep (probably preceeded by a god amount of consideration) is said to have helped the Russian scientist Mendelejew in 1869 to create his periodic table of the elements. Indium, the element with the exotic name, fitted into this system perfectly, while another of the gaps in the system was filled when in 1886 the professor of analytical chemistry in Freiberg, Clemens Winkler, discovered the element germanium. It matched exactly the predictions of Mendelejew about the properties of the missing substance.
A bronze plaque in Castle Square shows the atomic structure of these two elements discovered in Freiberg.