How expensive was this floor tile?

 

What we call London now used to be called "Londinium" (sounds like a radioactive element) back during the times when Romans lived there.  And archaeological digs that take place when they're building something new in London commonly find evidence of Roman habitation.

In this case, they found a lot more floor.  The floor of a fine Roman home, it appears.

Digging in the Shadows of London’s Shard, Archaeologists Discovered a ‘Once-in-a-Lifetime Find’: a Shockingly Intact Roman Mosaic

"The mosaics are believed to date from A.D. 175–225, and likely formed part of a luxurious dining room floor, in keeping with earlier discoveries in the area, which was known as Londinium, or Roman London, according to a press release issued by the company."

The article also says that the tile resembles patterns found in Germany, potentially indicating that tile masters were imported to London.  And that had to be expensive.