The excavating, setting forms, installing reinforcement (rebar/cables), and pouring concrete to create a stable base.

Foundations.

Concrete foundation at a construction site with workers and excavators, mountainous landscape in the background.
Construction site with concrete foundation walls and a worker installing form panels, with dirt and construction materials around, in a hilly area with trees and houses in the background.
Construction site with concrete walls being built, surrounded by snow and with a clear blue sky. Workers and construction equipment are visible.
Construction workers at a building site with a concrete pump truck, working on the foundation of a structure in a residential neighborhood with houses and trees in the background.
Construction site with steel rebar grid for concrete foundation, wooden formwork surrounding the area, and construction materials covered with orange and blue tarps.