Luxury living in Mountain Park. Welcome home. Welcome to One Jefferson, located on top of the Mountain Park neighborhood of Lake Oswego. We proudly offer studios, 1 bedrooms, 2 bedrooms and 3 bedrooms, in a variety of floor plans. Our apartment homes offer a serene setting surrounded by nature with amazing vies of the Portland landscape. We offer newly renovated homes with stainless steel appliances and granite counter tops in every home. included is a Free pass to mountain Park recreation center.