You can't visit San Francisco without taking a ride on one of its three cable car lines, which run up and down the steep hills of downtown. The Powell-Hyde cable car is perhaps the most adventurous, as the ascent up Nob Hill is steep enough to feel like a rollercoaster, but the Powell-Mason and the California lines also have their charms. Tickets are around $6, and the cars can be boarded at their turn-around stations or anywhere along the line. For those with further interest in the history of these clanging contraptions check out the Cable Car Museum in North Beach, which is open 10 a.m - 6 p.m. daily.