My favorite Era for ancient art is the Greek Era. Their techniques are fascinating and the things they come up with really are advanced for their time period, they really raise the bar for their era when it comes to architecture.
I'm not sure what era the renaissance took place in, but the art that emerged during the time of DiVinci still blows my mind. The frescos of the time are especially captivating due to the scale. If that doesn't count, define "ancient".