When was the sacrificing of animals ceased? What event(s) caused this? Was the ceasing of animal sacrifices commanded?

Since the temple was built in Yerushalaim by King Shelomo, sacrificial offerings can only be offered on temple mount in the place the copper altar stood. Since the destruction of the second temple [70 C.E] we were unable to rebuild it and offer our sacrifices there. Another obstacle is the fact we are all impure and have not yet found the Red Cow to purify us. We pray for the rebuilding of the third temple and the restoration of the Korbanot service many times daily and hope we will merit seeing that prayer fulfilled in our days.