Best Small-Group Istanbul Walking Tour: Hagia Sophia Museum and the Blue Mosque. Visit Istanbul’s must-see sites on this 3.5-hour small-group walking tour of the city. With an expert guide at your side explaining Istanbul’s contrasting cultures and history, you'll explore Hagia Sophia Museum, the German Fountain, the Hippodrome of Constantinople and the incredible Blue Mosque. Numbers are limited to 15 on this small-group Istanbul walking tour, ensuring you’ll see the best of the city with personalized attention from your guide. Book Now and Save 10% Off Best Small-Group Istanbul Walking Tour: Hagia Sophia Museum and the Blue Mosque.