Media celebrities, such as The Beatles, Pablo Escobar, Urbanus, Paul Newman and Frank Zappa were also frequently caricatured. Sleen also gave himself cameos in several stories. Very exceptional was the fact that all these jokes about past politics were not removed when the newspaper episodes were published in album format. This is the major reason why "Nero" provides readers with an overview of almost 60 years of post-war history in Belgium. Since Sleen worked without assistance for the majority of his career, he kept his drawing style simple and efficient. He had no time for elaborate detailed drawings and as a result many of his stories are filled to the brim with continuity errors or off-model drawing mistakes. Contrary to other comics, many readers accept this as part of "Nero"'s charm. Only when Dirk Stallaert took over the drawings did the art work become more technically detailed, with more attention towards space and perspective. During its 55-year course, a lot of regular characters joined the original duo of Nero and Van Zwam. During its heyday "Nero" was the second most popular Flemish comic strip, after "Suske en Wiske". The albums sold well, also because they were a lot cheaper than their main rival. From the late 1940s until the early 1960s all the stories were published on cheap paper and often smelt of fresh ink. During the 1960s Jef Nys' "Jommeke" overshadowed "Nero"'s sales among children. Attempts have been made to translate "Nero" to the Dutch, British, French, German and South African market. Except for in Wallonia and the Netherlands, the translated versions of "Nero" never caught on. Sleen has very rarely used his characters for merchandising or other commercializations. "Nero" was very influential for the development of comics in Flanders. Its loose drawing style and story lines replete with folly were an inspiration for "Urbanus", "Biebel", "Cowboy Henk", among others. Dutch artists like Martin Lodewijk ("Agent 327") and René Windig and Eric De Jong ("Heinz") are also notable fans. The Flemish comics prize Bronzen Adhemar is named and sculpted after the character Adhemar. In Turnhout, where the award ceremony is traditionally held, a huge statue of Adhemar can be seen in the Warande park since June 15, 1991. It was created by Frank-Ivo Van Damme.