The Eiffel Tower can grow taller in the summer due to thermal expansion. When temperatures rise, the metal structure absorbs heat and expands, causing the tower to increase in height. This phenomenon can result in the Eiffel Tower growing by up to 15 centimeters (about 6 inches). The expansion occurs because the iron material of the tower expands when heated, a common characteristic of metals. This subtle but measurable change demonstrates the dynamic nature of architectural structures and the influence of environmental conditions on them. Despite this seasonal growth, the tower remains stable and secure, showcasing the ingenuity of its design and construction.