Famous Problems in the History of Mathematics
History of math presented through the great problems that inspired mathematicians from Zeno to Cantor.
mathforum.org/isaac/mathhist.html
Mathematical Problems of David Hilbert, The
His influential address at the 1900 International Congress of Mathematicians outlined 23 research problems to be investigated in the coming century.
aleph0.clarku.edu/~djoyce/hilbert