These free, 45 minute guided tours of Brunel's massive engineering masterpiece set off from the Clifton Toll House on the eastern bank of the bridge. There’s no need to book.

Two hour Hard Hat Tours (£14) of the vaults below the Leigh Woods Tower take place regularly (around four times a week) from Easter to October. They're fairly strenuous and need to be booked in advance – see the website for details.