there were guards posted next to the raised dais at the end of the square where the emperor would give his address the next evening , guards posted at the ornate bronze gate the massive blackrock arch depicting high priests , high prods and emperors from throughout history , its name derived from a large bronze disc at its top and before he knew it he was passing through the entrance into the manganese palace itself , once having gone through the largest and most heavily-guarded checkpoint of them all .