Millions of people use the train network in London every day, travelling on the Underground, Overground and DLR services to get around the capital, without ever thinking too much about how the system works.
But hundreds of metres below the surface, a change is coming - a change so big that it could alter the way London works as a city.
Since its launch in May 2009, Crossrail has grown to become the biggest engineering project in Europe.
Over 10,000 workers are currently employed at over 40 construction sites across London and the south east, with over 100 million working hours already invested in the project.
The size of Crossrail means that it provides an invaluable experience for young workers looking to get into engineering.
One scheme that is aiming to help young people, particularly girls, into the field is Tomorrows's Engineers Week.
Run by organising body EngineeringUK, the scheme, which this year runs from November 7th-11th, travels to schools around the country looking to raise awareness of the work young people can get involved in on projects such as Crossrail, and the sheer range of jobs available in the engineering field.
Crossrail is set to increase central London's rail capacity by over 10 per cent upon its completion, and will cut journey times across the capital dramatically, as well as lowering congestion at many key points across the Tube network.
In total, Crossrail will include forty stations across its 100km route, including ten new stations at locations across central London, with Farringdon joining the likes of Paddington, Bond Street and Canary Wharf.
Testing of the new trains is set to begin in December 2017, with the line then due to open later in 2018 - and having seen the scale of the project so far, we have to say, we're pretty hopeful of the benefits it will bring.