Mansell, part of listed giant Balfour Beatty, will redevelop the Blists Hill Victorian town in Coalbrookdale, Telford.
The group will build a new visitor centre with 1,000sq m of space to serve as a new entrance to Blists Hill.
It will also build a Victorian street, to be called Canal Street, and more than 200 parking spaces, extend an external events area and demolish some existing buildings.
Work is to start immediately with the project due next Spring.
The contract will also see Birse Civils, another Balfour Beatty company, build railway lines, a sub-terrain clay-mine exhibit with associated surface buildings and a minehead.
Mansell divisional manager Steve Oldacre said: “This is a challenging project, and not just because it involves building an entire street that must look authentically Victorian".
"The museum must stay fully operational throughout the work and the main entrance will remain in use right up to the point that the new main entrance building is ready."