Archeological remains give clues to the use of nanotechnology materials in ancient times. A famous artifact from this period called the Lycurgus Cup resides in the British Museum in London.
The base of the Lycurgus Cup is made of glass and dates back to the fourth century A.D. (the gilded bronze base and rim were added later). What makes this cup unique is that its color changes from green (when illuminated from the outside) to red (when illuminated from within). What causes the color change? Transmission electron microscopy reveals that the glass contains nanoparticles of gold and silver. At the nanoscale, materials exhibit properties that are different from their macroscale counterparts. Most likely, the unique properties of this ancient Roman piece were created by accident as there are surviving pieces from this era that appear to be failed attempts to recreate this effect.