Álvaro Joaquim de Melo Siza Vieira, GOSE, GCIH, GCIP (born 25 June 1933), is a Portuguese architect, and architectural educator.
He is internationally known as Álvaro Siza (Portuguese pronunciation: ['a?v??u 'siz?]) and in Portugal as Siza Vieira (Portuguese pronunciation: ['siz? 'vjej??]).