Old stars in the Milky Way Galaxy record the history of nucleosynthesis in our part of the Universe stretching back almost to the beginning of time. From studies of the compositions of low mass stars which formed more than 10 billion years ago, we can trace the origin of the elements and identify sites of nucleosynthesis.At earliest times, the production of heavy metals in the Galaxy appears to have been by the weak s-process in massive stars, yielding the lighter n-capture elements (Sr-Y-Zr). The onset of the main r-process can be seen at [Fe/H]=-2.9, producing Ba, Eu, and other lanthanides; this onset is consistent with the suggestion that Type II supernovae from 8-10 Msun stars are responsible for the r-process. Until a metallicity of [Fe/H]=-2.4, the abundance pattern of the heavy (Z>56) n-capture elements in most giants is well matched to a dominant r-process nucleosynthesis pattern, rather than the traditional mix of r- and s-process products. Contributions from the s-process can first be seen in some stars with metallicities as low as [Fe/H]=-2.75, and are present in most stars with metallicities [Fe/H]>-2.3. The appearance of s-process contributions as metallicity increases reflects the longer stellar evolutionary timescale of the (low-mass) s-process nucleosynthesis sites. The abundances of the heavy metals in these metal poor stars show clear evidence for a large star-to-star dispersion in the heavy element-to-iron ratios. This condition must have arisen from individual nucleosynthetic events in rapidly evolving halo progenitors that injected newly manufactured n-capture elements into an inhomogeneous early Galactic halo interstellar medium.