Maria Keil (b. 1914 – d. 2012) developed a vast oeuvre in painting, illustration, engraving, tapestry and azulejos. As far these last are concerned she made a name by being the first Portuguese artist to give azulejos a modern look, based on the Portuguese azulejo-making tradition which she studied in depth, at a time when the national art community still considered azulejos as artisanal work. In 1959 the first underground stations of Metropolitano de Lisboa were inaugurated, along a project by her husband, the architect Francisco Keil do Amaral (b. 1910 – d. 1975), and Maria Keil was given ten stations to decorate. The revetments she designed between this date and 1972 reveal the complex simplicity that marks her production. In this panel, dated 1955, Maria Keil once again revisits Portuguese tradition by suggesting on one same azulejo simultaneously the chequered technique and the three-dimensional illusion of the "diamond point" pattern.