From AGI:

One of the most famous mosaics found in the Pompeii excavations, the one depicting the 'Battle of Alexander', is back, though as a copy, in its place of origin, the 'Casa del Fauno' of the ancient Roman city. The copy is faithful in its form, materials, size and colours to the original, and was made by the Ravenna International Mosaic Study Centre, who used 3 million mosaic pieces and thousands of support panels. The 'clone' will soon return to furnish the pavement of the building. Superintendent Piero Giovanni Guzzo explained: "The placing of the mosaic's copy will be part of a larger programme to appreciate areas around the Vesuvius, especially Pompeii. We intend to make visitors see the original look of the furnishing of the ancient buildings, also inviting them to visit the original decorations at the Naples Museum. [...] The 'Battle of Alexander' can be considered the most famous museum from ancient times. The original was a painting attributed to Philoxenos of Eretria for King Cassandrus at the end of the IV century BC. The mosaic was made in Pompeii following the 'opus vermiculatum' technique, and depicts a decisive moment in the Persian campaign which saw Alexander the Great against King Darius III. The original is in the National Archaeological Museum of Naples".

MF sent me a photo of this which I can't track down on the web (it's rather large ... if I can't find it on the web, maybe I'll shrink it down) ... it's very weird seeing this on a floor (which, of course, is where it would have been).