  Imagine an under water factory which is about $10 \mu$m long in each
direction. The factory is filled with machines, each typically a few tens of
nanometers long, which perform specfic tasks and operate in a well coordinated
manner. A cell, the structural and functional unit of life, is not very
different from this micro-factory. In this article, I begin with Alice's guided
tour of this micro-factory in her dream during which the guide shows her wide
varieties of the nano-machines in this factory. The style of presentation of
the first half of this article is inspired by Lewis Carrol's {\it Alice in
Wonderland}. In the second half, I introduce the methods of studying the
materials and mechanisms of the molecular machines through dialogues; the three
participants in this discussion are Alice, her elder brother Alex and her
father Albert. The style of presentation of the second half of this article, in
terms of a dialogue, is adapted from Galileo's {\it Dialogue Concerning the Two
Chief World Systems}. Albert, a professor of biophysics, emphasizes the crucial
differences between the mechanisms of the natural nano-machines and those of
their macroscopic counterparts. He also points out some practical applications
of this interdisciplinary research in biomedical science and nano-technology.
