Trolleys

You can't go to San Francisco w/o riding the famous cable cars (no matter how expensive or how long the line is!)...they are the only operating cable cars left in the world and the only moving National Historic Landmark! Piece of trivia we learned from the museum: cable cars (which are technically NOT trolleys) are mechanical (gripping the cables underground) while street cars are electrical (connecting the lines above the cars). Many big cities have operating electrical street cars so those are what you commonly see, but cable cars are unique to San Francisco alone!