The 17th century is decisive for the affirmation of the azulejo as an identitary art of Portugal. It was the time when the different uses were outlined: the pattern, figurative and ornament. In that sense, an in-depth knowledge of the azulejos of the era is essential to understand how the azulejo was conceived and used in our country, as opposed to in other places and cultures, and reflecting a very specific taste. One of the characteristics that then stood out, although it had its roots in the previous century, was how it was applied as a structuring element of architecture, throughout what were often monumental revetments, with pattern azulejos performing a key role. The Church was the main entity responsible for commissioning repeat azulejos, an extremely effective option for the often total revetment of the walls in its churches. This is one of the most fascinating aspects of the creative process of Portuguese ceramic painters: their capacity to invent and interpret themes and decorative motifs from various origins, a fusion of influences that led to the creation of a unique language. The multiplicity of solutions and proposals in the Portuguese pattern tiles of this period has no parallel in other European productions. In the transition between the 16th and the 17th century complex enxaquetado motifs were produced, chequered compositions reminiscent of medieval ceramic floors, consisting of elements of different shapes applied in strong diagonal lines, in which the white surfaces determined the visual rhythms. They might have simple contrasts in blue or green and white or contain decorative elements that made them richer, in what became known as enxaquetados ricos. Sometimes, false enxaquetados were made. These were possibly destined for spaces where the application could not rely on the work of more experiences azulejo-layers, or because they wished for an illusion of complexity, to overcome financial constraints of the commission. The patterns were structured using repetition modules of 2x2, 4x4, 6x6 and 12x12 azulejos – although there are a few very rare examples made up of an odd number – forming tapetes or carpets framed by borders or bars, very often with added friezes. These were essential for their integration in the architectural space, for the revetments could clad the entire wall from the floor to the ceiling coving, and indeed pillars, vaults and cupolas as well. Generally, patterns of smaller modules were applied to the lower part of the walls, the larger ones being reserved for the wall surfaces that were further away from the viewer, creating the illusion of proximity. At this time, azulejos were polychrome, using the colours blue, green and yellow, although patterns were also produced of blue on a white background. Some of the patterns were produced during the Iberian Union of 1580 to 1640, no doubt because motifs with a Spanish origin were made in Lisbon. This is the case of the motifs called ponta de diamante or diamond-point, from Seville or Talavera, known in Spain as clavos (nails). Their application varied considerably with the introduction of central and lateral elements that achieved new aesthetic proposals. Another memory of the political and economic coexistence on the Peninsula are the so-called patterns of parras or vines, an aesthetic import of a Seville or Talavera creation destined for the Escorial Palace. During a first production period note also the patterns having an Italian-Flemish influence, some of which are rare modules directly inspired on paving motifs. A huge variety of patterns and variations thereof appeared throughout the century. They can be grouped into families, as João Miguel dos Santos Simões did in his pioneering study. Some with their maçarocas (ears of corn) and camellias are manifestations of a taste for the exotic. They are an identitary aspect of Portuguese azulejos inspired by Turkish textiles or China porcelain. Groups such as the laçarias or bows took references from the Hispano-Moresque azulejos of the first half of the 16th century. Note also the existence of patterns that are impossible to group together as they are rare or even unique, with strongly dynamic rhythms, some even confusingly so, inspired on fabrics, leather and metalwork. As a whole they attest most eloquently to the creativity of Portuguese 17th century potteries.