The Interpretation of Dreams by Sigmund Freud Chapter 5 Page 18

In dreams of men one often finds the cravat as a symbol for the penis; this indeed is not only because cravats hang down long, and are characteristic of the man, but also because one can select them at pleasure, a freedom which is prohibited by nature in the original of the symbol. Persons who make use of this symbol in the dream are very extravagant with cravats, and possess regular collections of them. All complicated machines and apparatus in dream are very probably genitals, in the description of which dream symbolism shows itself to be as tireless as the activity of wit. Likewise many landscapes in dreams, especially with bridges or with wooded mountains, can be readily recognized as descriptions of the genitals. Finally where one finds incomprehensible neologisms one may think of combinations made up of components having a sexual significance.