The Swiss tourist information office has I pods that have 4 and 8 hour walking tours that consist of 6 routes. The cost is around ch4 and ch6 for the day. These tours start from old town marketplace. Many old building , some of them housed the various trade Guilds of the 1700’s.
“Basel has a beautiful medieval old town center, a vibrant Carnival, and several world class art museums built by architects like Renzo Piano, Mario Botta and Herzog & De Meuron. Basel is also rich in architecture old and new, with a Romanesque Münster (cathedral), a Renaissance Rathaus (town hall), and various examples of high quality contemporary architecture, including more buildings by Herzog & De Meuron, Richard Meier, Diener & Diener, and various others.” -(Wikitravel)