Biographical Info on MacTutor

If, good friend, thou mindest to obtain from any small cube a cube the double of it, and duly to change any solid figure into another, this is in thy power; thou canst find the measure of a fold, a pit, or the broad basin of a hollow well, by this method, that is, if thou thus catch between two rulers two means with their extreme ends converging . . . Thus may it be, and let any one who sees this offering say
"This is the gift of Eratosthenes of Cyrene".       

Eratosthenes epigram on a column in Alexandria

Measuring the Circumference of the Earth:

Eratosthenes' Method
Measure the Earth Sci Project
Eratosthenes & the Earth's Diameter
Math Forum Explains EM

Prime Number Sites:

Prime Number Quiz
Prime Number Machine
Eratosthenes Sieve (Javascript demo)
Eratosthenes Sieve - another demo
Murderous Maths Prime Game
The Prime Pages
Largest Known Primes
Patterns in Prime Numbers
Prime Number Cascade

Prime numbers, trigonometry, math and geography,large numbers, proportion and ratio.

Eratosthenes Measures the Earth

287 BC to 212 BC in Syracuse, Sicily Greece