Steen Eiler Rasmussen (1898-1990) was a Danish architect and town-planner, professor at the Royal Danish Academy of Fine Arts , and a prolific writer of books and essays. Like his compatriots Hans Christian Andersen and Johannes Vilhelm Jensen he travelled extensively, and his observations often became basis for his writings. His bibliography (1973) lists 536 items.

One of his most important books was London. It was first published in Danish in 1934, in English (as London, the Unique City) in 1937. When this edition was re-issued in 1948, Rasmussen had added two Postscripts: "For English readers only", and "For American readers only". A shorter version was published as a paperback in 1960.

Other influential books by Steen Eiler Rasmussen are Towns and Buildings (1951), and Experiencing Architecture (1959).

It has been stated that every English and American city-planner knows his "Rasmussen".