The present article focuses on the work of João Miguel dos Santos Simões (1907-1972), a researcher, historian, scholar and promoter of Portuguese azulejos and their use in Portugal, as well as the founder of the National Azulejo Museum. Santos Simões played a very important role in the identification both of the azulejo’s specific characteristics and of their use in Portugal. He was, in the 20th century, one of the most important promoters of the azulejo as a distinctly Portuguese art form. His main theoretical contribution concerns the recognition of the azulejo’s unique expression in Portugal — and, by extension, in Brazil. Its use gave rise to monumental decorations and helped shape the architecture in original ways. Apart from identifying the main characteristics of the use of azulejos in Portugal, Santos Simões also compared it to the situation in other countries, namely in Spain. Moreover, he studied the azulejo as a touristic phenomenon, a subject whose topicality warrants, according to the author of the present article, a detailed examination.