A layer of peptidoglycan found outside of the cytoplasmic membrane. The peptidoglycan is relatively thick (20-80nm) and retains the primary stain of the Gram procedure, thus cells appear blue after Gram stain. The cell walls often contain teichoic acids (acidic anionic polysaccharides) bound to the peptidoglycan. Examples of this component are found in Gram-positive bacteria.