Concrete / cement foundation.
Demolition, excavation and construction of 192 7th Avenue on the corner of 7th Avenue South and 11th Street, NYC.
Rebar (short for reinforcing bar) is collectively known as reinforcing steel and reinforcement steel,it is a steel bar or mesh of steel wires used as a tension device in reinforced concrete and reinforced masonry structures to strengthen and hold the concrete in compression.
Concrete is strong under compression, but has weak tensile strength. Rebar significantly increases the tensile strength of the structure. Rebar's surface is often patterned to form a better bond with the concrete.