This lecture discusses the expansion of the Palace of Versailles to accommodate the increasing number of visitors, focusing on the architectural challenges and solutions, such as creating new spaces, annexing basements, and integrating historical elements while harmonizing modern additions. The instructor explores the construction of a grand staircase to introduce natural light, guide visitors, and connect the palace to the gardens, showcasing the transformation of vaults into shops, dining areas, and an auditorium with a dual roof design for acoustic purposes.