As the original freeway begins, it passes under an extension to the 1925 Avenue 26 Bridge, one of four bridges over the Arroyo Seco that predate the parkway's construction. A southbound exit and northbound entrance at Avenue 26 complement the Figueroa Street ramps, and similar ramps connect Pasadena to both directions of I-5. SR 110 continues northeast alongside the Arroyo Seco, passing under the L Line light rail and Pasadena Avenue before junctioning Avenue 43 at the first of many folded diamond interchanges that feature extremely tight (right-in/right-out) curves on the exit and entrance ramps. The next interchange, at Avenue 52, is a normal diamond interchange, and soon after is Via Marisol, where the northbound side has standard diamond ramps, but on the southbound side Avenue 57 acts as a folded diamond connection. The 1926 Avenue 60 Bridge is the second original bridge, and is another folded diamond, with southbound traffic using Shults Street to connect. The 1895 Santa Fe Arroyo Seco Railroad Bridge (now L Line) lies just beyond, and after that is a half diamond interchange at Marmion Way/Avenue 64 with access towards Los Angeles only. After the freeway passes under the 1912 York Boulevard Bridge, the pre-parkway bridge, southbound connections between the freeway and cross street can be made via Salonica Street. As the Arroyo Seco curves north to pass west of downtown Pasadena, the Arroyo Seco Parkway instead curves east, crossing the stream into South Pasadena. A single northbound offramp on the Los Angeles side of the bridge curves left under the bridge to Bridewell Street, the parkway's west-side frontage road.