Built to last?

This is the old Ellon Academy undergoing demolition. It was built in 1979 and is where our two children received their secondary education. It closed in 2015 when a new school opened on the outskirts of the town. The original school, which was replaced by this 1979 concrete structure, was built in good Aberdeenshire granite between 1876 and 1911 and still stands in good condition, although unused. Why do we build such rubbish these days?