The Italian Job

Charlie Croker (Michael Caine), a Cockney criminal, is released from prison with the intention of doing a "big job" in Italy. He soon meets with the widow (Lelia Goldoni) of his friend and fellow thief Roger Beckermann (Rossano Brazzi), who was killed by the Mafia while driving a Lamborghini Miura in the Italian Alps. Mrs Beckermann gives Croker her husband's plans for the robbery that attracted the hostile attention of his killers, which detail a way to steal 4 million dollars in the city of Turin and escape to Switzerland.
Croker breaks back into his former prison to convince Mr. Bridger (NoÃ«l Coward), the head of a huge criminal empire, to finance the plan. Bridger, who has bribed almost all of the prison guards to work for him, initially rejects the plan, but changes his mind after he learns Fiat is set to build a new factory in China.
With Bridger's backing, Croker recruits computer expert Professor Peach (Benny Hill), his girlfriend Lorna (Maggie Blye) and a team of thieves and drivers. The plan calls for Peach to replace the programme in the computer controlling Turin's traffic control system, creating a paralysing traffic jam that will allow the thieves to escape with the gold in three Mini Cooper S getaway cars.[7]
After planning and training, Croker and crew set out for Turin. Mafia boss Altabani (Raf Vallone) and his underlings are waiting in the Alps at the same pass where they killed Beckermann. Altabani warns Croker that the Mafia are aware of the gang's intentions and smashes their Jaguar E-Type cars, sending Croker's personal Aston Martin DB4 drophead off a cliff. Croker tells Altabani that Mr. Bridger will avenge their deaths by attacking the Italian community in Britain. Altabani lets them go, ordering them to return to England. Instead, they proceed with the plan, replacing the traffic control system's magnetic tape data storage reels. On the day of the robbery, Croker sends gang member Birkinshaw, disguised as a football fan, to jam the closed circuit television cameras that monitor traffic. The substitute data reel then causes widespread traffic chaos. The gang converge on the gold convoy, overpower the guards, and tow the armoured car into the entrance hall of the Museo Egizio. There, the gang transfer the gold to the Minis.
Altabani recognises that "If they planned this jam, they must have planned a way out." Pursued by the Turin police, the three Minis race through the shopping arcades of the city, speed down stairs, jump between rooftops, and finally escape the traffic jams by a pre-planned route across a weir. The getaway is timed perfectly, and they throw off the police by driving through a large sewer pipe. As Mr. Bridger receives the cheers and adulation of his fellow prison inmates, the gang drive the Minis into the back of a moving customised coach. They then unload the gold and dispose of the Minis by pushing them off the mountainside.
The rest of the gang, having sneaked out of the city in a minibus while disguised as football supporters, rendezvous with the coach in the Alps. On the looping mountain roads, driver "Big" William (Harry Baird) loses control of the coach. The back of the bus is left teetering over a cliff and the gold slides towards the rear doors. As Croker attempts to reach the gold, it slips further. The film ends on a literal cliffhanger with Croker announcing he has a "great idea".

Question: Where do the Minis drive to throw off the police?
Answer: through a large sewer pipe