Plato thought that the circle was a symbol of the divine. Alberti, an Italian architect, considered it the perfect shape. But no one was more obsessed with the circle than Guarino Guarini, a brilliant Baroque architect. His buildings are made of concave and convex spaces delineated by circles. One of his most important works, the church of Santa Maria da Divina Providência in Lisbon, was famous for its undulating facade. Sadly, the church was destroyed by the 1775 earthquake.

By happenstance, the circular shapes included in Guarini’s treatise, Architettura Civile, resurfaced in Portugal in the 20th century in the design of the popular bolo bolacha (biscuit cake). This cake is made with the circular Maria biscuits invented in 1874 by an English baker to celebrate the marriage of the Duke of Edinburgh with the Russian Duchess Maria Alexandrovna. To make the cake, the biscuits are dipped in strong coffee, layered with buttercream and then assembled according to designs…