821.5 centimeters is equivalent to 323.66 inches.
To put this into perspective, here are some comparisons of known objects of similar size:
1) The length of a standard grand piano is about 300 centimeters, so 821.5 centimeters is slightly longer than the length of a grand piano.
2) A typical door is about 80 inches tall, so 821.5 centimeters is roughly 4 times the height of a door.
3) The height of the Eiffel Tower is 324 meters, which is equivalent to 32400 centimeters. Therefore, 821.5 centimeters is about 1/40th the height of the Eiffel Tower.
4) The average adult male is about 175.3 centimeters tall, so 821.5 centimeters is almost 5 times the height of the average adult male.