I have an outdoor shopping center that has a water fountain 35 years
old. the ceramic tile inside the fountain has seen its finer days and
needs to replaced. The construction people say the tile is embeded
too firmly to be removed and that they only way to improve is to buy
tile designed to
be affixed over exisiting tile.

I don't know about such tiles. Does the method really work? Where
on the web can I find
vendors of this type of tile?

best, Aaron