Once it is taken, it belongs to government, not to the former owner.
The concept is that government would not take it for any reason but the common good; and would pay a fair price for it. Neither of those things is still true, if they ever were true in any way other than pure theory.
BTW, the most famous eminent domain case in the U.S., Kelo v. New London (Connecticut) involved a taking for purposes of allowing a pharmaceutical company to take land in a blighted area to build something new there. The property owner challenged on the ground that is not taking land for a public purpose, for which eminent domain is supposed to be used, but a taking for a private purpose.
http://en.wikipedia.org/wiki/Kelo_v._City_of_New_London The majority opinion was written by one of the most liberal Justices ever to sit on the Supreme Court, Stevens (appointed by a Republican President to whom Stevens was a great disappoint, much as Eisenhower rued nominating Earl Warren). Joining Stevens in the majority were Justices Kennedy, David Souter (another disappointment to a Republican President), Ruth Bader Ginsburg and Stephen Breyer.
Not what I would have expected.