The spidery towers of the 1906 Transporter Bridge rise over the river, about a mile south of the city centre. A remarkable piece of Edwardian engineering, it can carry up to six cars across the river in a gondola suspended beneath the high-level track, while still allowing high-masted ships to pass beneath. It's the largest of eight such bridges remaining in the world.
If you're planning on driving across and straight back again, you may as well consider paying the day visitor rate (adult/child £2.50/1.50) which includes access to the motor house and high-level walkway.