The Temple Institute: In-Depth Temple Study: The Crimson Line
 
The Crimson Line

The Crimson Line was a thin red strip that ran all along the mizbeach and divided its height into two. The upper part was five cubits, including the height of the horns. The bottom half was five cubits, including the base. * Some offerings, such as the burnt and peace offerings, required their blood to be dashed upon the bottom half of the mizbeach. The priest performing this service would stand on the floor of the court. For other offerings, such as the outer sin offering, the blood was required to be applied to the upper part of the mizbeach. The Mishna states that the line was designed to "separate between the upper blood and the lower blood." 
Contents:   Part I,    Part II,    Part III,    Part IV,    Part V,    Part VI,    Part VII