Last spring, York's Guildhall found itself in dire straits. Water dripped from the 15th-century meeting hall's ceiling, and cracks in one of its walls were so large that visitors could stick a hand straight through them, reported David Dunning for local radio station Minster FM at the time. That fall, the local government launched a £16.5-million construction project aimed at restoring the historic building -- which has stood on the banks of the River Ouse in the northeastern English city for more than 500 years -- to its former glory. But the work has revealed more than just dilapidated walls:...