Business and Education South Yorkshire, Sheffield Hallam University and Sheffield Industrial Museums Trust worked in partnership to organise the event at Sheffield's Kelham Island Museum.
The teams of pupils aged five to 11 from over 90 primary schools came up with buildings including a town hall, stately home, a market square with stalls, railway station and a church.
Leading construction industry experts helped the youngsters to create their projects as part of the Build It day.
Event co-ordinator Mary Milburn said: "Build It is a great chance for primary school pupils to work together in teams and learn more about the construction industry.
"This event is action packed every day from start to finish, with pupils getting the chance to find out more about the issues that are associated with the construction industry."