The revolving door was invented in 1888, by Theophilus Van Kannel.

The number Pi (the ratio of the circumference to the diameter of a circle) can't be expressed as a fraction, this means it is an irrational number. When written as a decimal it never repeats and never ends.

The first spam message was transmitted over telegraph wires in 1864.

A M A Z I N G   F A C T S