An article on the history of Litfaßsäulen should begin with the problem they were designed to solve. In the middle of the nineteenth century, German cities (and, for that matter, many European cities, some of which adopted their own version of Litfaßsäulen) were cluttered with advertisements on every flat surface. These were untidy, and the glue sometimes caused damage to the facades of buildings. Advertising has become much more common over the past few decades, and companies competed fiercely for public attention with garish posters.
Ernst Litfaß's idea for a more aesthetically pleasing way to display these advertisements was to place columns on the street, to provide dedicated space for the display of advertisements. These columns were three meters high, and attractively designed. Litfaß pioneered the system in Berlin in 1855, and the city commissioned 150 Litfaßsäulen, which soon became recognized as an iconic feature of the city. The idea quickly spread throughout Germany, and today there are over 50,000 Litfaßsäulen in use throughout the country.
Depending on the length and scope of your essay, you might trace the development of Litfaßsäulen to include telephone booths or vending machines. You might also look at the adoption of the idea in other countries, where these advertising columns are called by different names but clearly replicate Litfaß's idea.