In an interview -- not included in Scharnhorst's collection nor in his
updates -- the original which most likely ran in the New York _Mail
and Express_ but was reprinted in the Wheeling (West Virginia) _Register_
(now available intext searchable newspaper databases) titled
"Twain Interviews Himself" dated March 29, 1882 Twain is quoted:

"Perhaps you might ask me about Oscar Wilde, or Roscoe Conkling, or
Blaine, at the obelisk...."

The obelisk in Alexandria, Egypt was in the news in February 1882
as the site of the discovery of a stash of rare coins dating back
2,200 years. The report of the study of the coins found at the
obelisk was released in Feb. 1882.

I think it is more likely Blaine was connected to this story rather
than an American landmark, perhaps as a political sort of joke, but
I have not found an exact quip thus far.

Barb