Basel's Altstadt spreads across just under one square kilometre, yet it harbours over 300 buildings protected under cantonal heritage law. The quarter's core—Marktplatz, Münsterplatz, and the narrow lanes linking them—traces a street grid unchanged since the 14th century, when Basel served as a crossroads between the Holy Roman Empire, Burgundy, and the Swiss Confederation. The red sandstone Rathaus, completed in 1514, still houses the cantonal parliament; its courtyard frescoes, painted by Hans Bock the Elder in 1608, depict allegories of justice that were controversial enough to prompt a public debate recorded in the city archives. English-language guided walks gained traction in Basel after the 2015 expansion of the Basel Tourism office on Steinenberg, which began recruiting multilingual guides trained in art history and urban planning. The demand reflected a shift: by 2020, nearly 60% of overnight visitors to Basel arrived from outside the German-speaking world, with English the most requested language for cultural programming. Today's Basel walking tour in English offerings span Old Town heritage routes, Rhine promenade circuits, and thematic itineraries that follow the trail of the 1431 Council of Basel or trace the city's pharmaceutical legacy through corporate campuses and museum collections. The Münster Cathedral, consecrated in 1019 and rebuilt after the 1356 Basel earthquake, anchors most guided itineraries. Its twin towers—the taller Georgsturm reaches 64.2 metres—frame a Romanesque-Gothic interior where the tomb of Erasmus of Rotterdam lies beneath a bronze epitaph cast in 1538. From the Münster terrace, guides point out the Pfalz viewing platform, 20 metres above the Rhine, where medieval sentries monitored barge traffic. The Mittlere Brücke, Basel's oldest Rhine crossing, dates to 1226; its current stone arches were laid in 1905, but the bridge chapel, a 15th-century addition, survived the reconstruction. Walking tours linger here to explain the Rheinsprung, the steep lane ascending to the cathedral, which medieval pilgrims climbed en route to Santiago de Compostela. Marktplatz, the commercial heart since Roman Basilia, hosts a daily produce market beneath the Rathaus arcade. The square's guildhalls—Zunfthaus zum Schlüssel, Zunfthaus zur Hausgenossen—bear coats of arms granted between 1260 and 1515, when Basel's trade guilds wielded political power equal to the patrician families. English-speaking guides often pause at the Tinguely Fountain on Theaterplatz, a 1977 kinetic sculpture by Jean Tinguely that pumps Rhine water through ten mechanised iron figures, a postmodern counterpoint to the Baroque facades encircling it. The fountain marks the edge of the Altstadt and the start of the Grossbasel–Kleinbasel axis, the cultural divide that persists in local dialect and civic identity despite four centuries of political union.