Merida was founded in the years immediately preceding the birth of Christ on the Roman crossroads linking Toledo and Lisbon, with Salamanca and Seville. Known at its peak as a miniature Rome, its monuments, temples, and public works make it the site of some of the most celebrated Roman remains in Spain. In this work, the author studies the theatre and amphitheatre from the point of view of construction and, in particular, the phases of wall building. The result is a detailed, course-by-course, picture of these two famous structures and their wider contexts, offering a new archaeological basis for the history of the city of Merida.