The central downtown area is bounded by the Willamette River on the east and by the curve of I-405 on the other sides. Compact, clean and pedestrian-friendly, with short, 200ft square blocks and three historic districts, the city's core is a destination and gathering spot for residents and workers from all over the city. Parks, fountains, public artworks and a rich texture of building and street materials add to its appeal. Brick-paved Transit Malls (one-way streets reserved for buses) completed in 1978 along Southwest Fifth and Sixth Avenues bisect the main retail and business district.