  We present a detailed study of the evolution of massive stars of masses 15,
20, 25 and 30 $\msun$ assuming solar-like initial chemical composition. The
stellar sequences were evolved through the advanced burning phases up to the
end of core oxygen burning. We present a careful analysis of the physical
characteristics of the stellar models. In particular, we investigate the effect
of the still unsettled reaction $^{12}$C($\alpha$,$\gamma$)$^{16}$O on the
advanced evolution by using recent compilations of this rate. We find that this
rate has a significant impact on the evolution not only during the core helium
burning phase, but also during the late burning phases, especially the shell
carbon-burning. We have also considered the effect of different treatment of
convective instability based on the Ledoux criterion in regions of varying
molecular weight gradient during the hydrogen and helium burning phases. We
compare our results with other investigations whenever available. Finally, our
present study constitutes the basis of analyzing the nucleosynthesis processes
in massive stars. In particular we will present a detail analysis of the {\it
s}-process in a forthcoming paper.
