1. It was built after the rebellion of Boadicea and the massacre of the people of London. It was intended as a military bridge connecting the Citadel of London, built immediately after that event, with the southern ports.
2. The construction of a stone bridge over a broad, deep, and tidal river would have been a work involving a long time and immense cost. Trajan’s Bridge over the Danube was built about the year 104 A.D., but the Danube is not a tidal river. There is no example of a stone bridge over a tidal river, that I know of, belonging to this age.
3. The engineers who formed part of the army would naturally be ordered to build the bridge, and would do so after the manner which they had learned and practised with other military bridges.
4. The accounts of and reference to the bridge during the next thousand years or so clearly suggest a wooden bridge. Snorro Sturleson, the Icelander, speaks of it as wooden and sustained by piles. The planks which formed the mainway must have been loosely laid together with gaps between, for a large number of Roman coins have been found in the bed of the river below; these had apparently rolled through. The bridge is reported to have been carried away or greatly damaged in 1091. It was burned in 1136.
5. The first stone bridge of the twelfth and thirteenth centuries took thirty years to complete. A military bridge, such as I conceive the first London Bridge to have been, could not be allowed to remain unfinished for years.
The course of events, as I have already suggested, was as follows:—
1. London was unprotected until after the massacre by the troops of Boadicea.
2. The importance of the place was then apprehended, and the Roman Citadel on the eastern hill over the Walbrook was constructed to protect the port and the town, and contained the garrison, the officers, and the officials.
3. The walls of the Citadel were built of stone from the Kentish quarries. The bridge, however, was built of wood, as being convenient, cheap, and easy of construction.
There were two models to choose from—perhaps more, but the two will suffice.