P.17 of Rulebook
"To replace a building or wonder, first the old building or wonder
is removed from the board. If it is a building, it is returned to
the market. If it is a wonder, the wonder marker and card are
returned to the box and may not be rebuilt for the remainder of
But you are talking about "replacing" a wonder. It is possible to have more than a wonder in the same city if the new one doesn't make the old one obsolete, isn't it? In the computer game...it definitely was.