  We report direct laser cooling of a symmetric top molecule, reducing the
transverse temperature of a beam of calcium monomethoxide (CaOCH$_3$) to
$1.8\pm0.7$ mK while addressing two distinct nuclear spin isomers. These
results open a path to efficient production of ultracold chiral molecules and
conclusively demonstrate that by using proper rovibronic optical transitions,
both photon cycling and laser cooling of complex molecules can be as efficient
as for much simpler linear species.
