In the 19th century, cannon were mounted on the rooftop and fired on ceremonial occasions.

One was used regularly as the ‘noon gun’, firing at the midday in response to a telegraph signal from Greenwich Observatory in London.  After a number of accident – in one of which a gunner was killed – the practice of firing the cannon was eventually discontinued in the 1850s and the guns were later removed.*

*Information from Newcastle Castle guidebook (Society of Antiquaries of Newcastle upon Tyne).

From Bridges on the Tyne:

The Swing Bridge has always been one of the most interesting bridges on the Tyne, as until the Gateshead Millennium Bridge came along, it was the only one that moved. Opened in 1876, it was necessary to replace the old Georgian Bridge in almost the same location which was low level and prevented larger vessels from moving up river or above bridge as it was called. This meant that keels were needed to transport coal from the riverbank staiths at Dunston, Derwenthaugh and beyond to the ships further down river, an inefficient and time-consuming process. Armstrongs factories at Elswick were held back due to the impossibility of ships reaching there.