A £2m cash boost will help make sure generations of visitors will be transported back through time to the birth of the railway.
Shildon Railway Village was awarded the money from the European Regional Development Fund last week bringing the total investment in the project to £10m.
Half of the money will be spent on linking the existing buildings at the Timothy Hackworth Museum to its new 6,000 sq m collections centre.
The open space between the two buildings, about 600m, will also be upgraded to incorporate interpretation and art work.
The Railway Village will house up to 60 historical vehicles from the National Collection.
It is expected that about 50,000 people will visit it each year including schools and large parties which will use it for educational purposes.
There will be modern, interactive interpretation of the exhibits plus a 'living' workshop where local apprentices will be trained in the skills needed to restore and conserve railway vehicles.
Norman Vaulks, chief executive of Sedgefield Borough Council, said: "This is more wonderful news for the Shildon Railway Village.
"Support from OneNorth East and the European Regional Development Fund was absolutely crucial to this project and we are delighted to have their backing.
"With the capital funding in place, we can now concentrate on developing the content of the new building and ensuring it will be a first class visitor attraction."
Sustainability has also been a major consideration in designing the village. The new building will feature a rainwater harvesting system, driven by a wind turbine, to recycle rainfall for use in the steam locomotives.
Photovoltaic roof tiles will also turn sunlight into energy to produce the electricity required to both heat and light the building.
Andrew Scott, head of the National Railway Museum, said: "This money adds vital international backing to a project that has already attracted tremendous support from partners across the North East, as well as substantial grant aid from both regional and national funding bodies.
"It demonstrates just how important to the future of the region Shildon Railway Village is considered to be and how determined everyone is to ensure that the new attraction will succeed."
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