It's comedy week on Guardian Cities, and we're starting with the relationship between sitcoms and the urban environments they portray. New York and London are popular, of course, but from San Diego and Philadelphia to Slough and Sheffield, the cities captured in comedy TV and movies aren't always the usual suspects.

Have you eaten at Tom's diner from Seinfeld? Perused the shelves at the bookshop in Notting Hill? Found a frozen banana stand in LA? We want to see you in your favourite comedy locales – whether you ended up there unwittingly or made a special pilgrimage. Share your pictures, videos and experiences with GuardianWitness and we'll feature the best on Guardian Cities. Just click on the blue 'Contribute' button, or if you're out and about you can download the free GuardianWitness app for smartphones.

• GuardianWitness is the home of user-generated content on the Guardian. Contribute your video, pictures and stories, and browse news, reviews and creations submitted by others. Posts will be reviewed prior to publication on GuardianWitness, and the best pieces will feature on the Guardian site.