Built up by the discovery or iron ore nearby and the development of the steel industry, Lake Oswego has transcended its industrial roots to become a popular and scenic tourist destination. Located just south of Portland on the Willamette River, the city features a number of parks and forested land. Outdoor activities are at the fore in Lake Oswego, however there are also shopping and dining opportunities available for visitors to enjoy. A historic walking tour sponsored by the local Chamber of Commerce is available in downtown Lake Oswego and presents a showcase of notable heritage sites. Visitors during the spring through autumn are encouraged to explore the Lake Oswego Farmers Market, held every Saturday from May to October. The Lake Oswego Daffodil Festival is held each April and celebrates the blooming of spring flowers. For scenic vistas and a unique experience, the Willamette Shore Trolley reveals the region and takes riders through what they call Oregon's Darkest Tunnel.