The engine house providing the power to operate the Cross Keys Bridge is located at the south-east corner of the property around the railway station. {1} The engine house was built in 1897, and houses hydraulic machinery by Sir W.G. Armstrong, Whitworth and Co. Ltd. It is of iron and red brick and features slate roofs. There is a ribbed iron tower with a hipped roof and overhanging eaves. The building is connected underground to the Cross Keys Bridge. For the full description and the legal address of this listed building please refer to the appropriate List of Buildings of Special Architectural or Historic Interest. {2}