Sherlock is a crime drama television series based on Sir Arthur Conan Doyle's Sherlock Holmes detective stories. Created by Steven Moffat and Mark Gatiss, it stars Benedict Cumberbatch as Sherlock Holmes and Martin Freeman as Doctor John Watson. Thirteen episodes have been produced, with four three-part series airing from 2010 to 2017, and a special episode that aired on 1 January 2016. The series is set in the present day, while the one-off special features a Victorian period fantasy resembling the original Holmes stories. Sherlock is a co-production of the British network BBC and the American station WGBH Boston for its Masterpiece anthology series on PBS, along with Hartswood Films, with Moffat, Gatiss, Sue Vertue and Rebecca Eaton serving as executive producers. The series is primarily filmed in Cardiff, Wales, with North Gower Street in London used for exterior shots of Holmes and Watson's 221B Baker Street residence.