The Bridge of the Americas — originally called the Thatcher Ferry Bridge — was completed in 1962 and was for decades the only fixed link across the Panama Canal. It carries the Pan-American Highway over the Canal's Pacific entrance and has a certain elegance as a piece of mid-century engineering: a steel arch bridge with a main span of 344 metres, rising high enough to let the largest ships of the era pass beneath.
You can drive or walk across the bridge, though it's more of an infrastructure sight than a destination in itself. The view from the middle, looking north up the Canal's Pacific approach with ships moving in both directions, is good. The newer Centennial Bridge (2004) has taken most of the traffic, leaving the Bridge of the Americas somewhat quieter and more amenable to pedestrian crossing.