  Invisibility cloaks, a subject that usually occurs in science fiction and
myths, have attracted wide interest recently because of their possible
realization. The biggest challenge to true invisibility is known to be the
cloaking of a macroscopic object in the broad range of wavelengths visible to
the human eye. Here we experimentally solve this problem by incorporating the
principle of transformation optics into a conventional optical lens fabrication
with low-cost materials and simple manufacturing techniques. A transparent
cloak made of two pieces of calcite is created. This cloak is able to conceal a
macroscopic object with a maximum height of 2 mm, larger than 3500
free-space-wavelength, inside a transparent liquid environment. Its working
bandwidth encompassing red, green and blue light is also demonstrated.
