The following essays are the proceedings of the symposium “Systems of History: George Kubler’s Portuguese Plain Architecture” held at Centro de Estudos Sociais September 7th 2012. This symposium was a celebration of many things: George Kubler’s 100th birthday; The Shape of Time 50th anniversary; and Portuguese Plain Architecture 40th anniversary. This was the year to celebrate Kubler, and we joined other celebratory conferences that happened throughout the year and to resonate a special note about his work in Portugal and the influence of his book: Portuguese Plain Architecture: Between Spices and Diamonds, 1521-1706 (1972).