The Shrine of the Immaculate Conception.  Fodor's has a neat
story:<blockquote>During the Battle of Atlanta, Thomas O'Reilly, the
church's pastor, persuaded Union forces to spare his church and several
others around the city. That 1848 structure was then replaced by this
much grander building, whose cornerstone was laid in
1869.</blockquote>It's a little sad that, while the pastor managed to
save the church from war, it was replaced twenty years later anyway. 
(Incidentally, it burned in the 80s and had to be significantly
restored.)<p />Frankly, it doesn't look impressive to me.  I originally
thought <a target=_blank href="IMG_4267.html">this church</a>, that I
saw earlier on the other side of the block, must've been the famous one.