 In around 1770 the neoclassical architect Robert Adam designed Pulteney Bridge , a three @-@ arched bridge spanning the River Avon . He used as his prototype an original , but unused , design by Andrea <unk> for the <unk> Bridge in Venice . Adam also submitted plans for the new Assembly Rooms but these were rejected as too costly . John Wood , the Younger raised funding for the construction of the Assembly Rooms by the use of a <unk> , an investment plan that is named after the Neapolitan banker Lorenzo de <unk> , who is credited with <unk> it in France in 1653 . It combines features of a group annuity and a lottery . Each <unk> pays an agreed sum into the fund , and thereafter receives an annuity . As members die , their shares <unk> to the other participants , and so the value of each annuity increases . On the death of the last member , the scheme is wound up . Construction started in 1769 and was completed in 1771 , when a grand opening was held . 
