Blackfriars Bridge - 1869 - London, UK - Bridge Date Stones and Plaques on Waymarking.com

A plaque, at the northern end of the bridge, tells us:

Corporation of London
Blackfriars Bridge
standing on the site of the original bridge named after
William Pitt the Elder in 1760. Constructed and maintained
without burden upon public funds out of monies derived from
Bridge House Estates Trust

First opened 6th November 1869 by
Her Majesty Queen Victoria
widened and reopened 14th September 1909 by
The Rt. Hon. Sir George Wyatt Truscott. Bart., Lord Mayor

The Tour UK website tells us:

"In 1753 it became obvious that a new bridge was required to make a gateway to the capital. This would be the third bridge to be built across the Thames in central London, after London Bridge and Westminster Bridge.

A competition was held in 1759 to find the best design and the winner, Robert Mylne, was appointed to build the bridge in 1760. The bridge had nine elliptical arches, resting on slender, pointed cutwaters and supported by double Ionic columns.

You can see the the designs of this bridge on the walls of the southern pedestrian subway under Blackfriars Bridge.

Finished in Portland stone, the structure was 995 ft long and 42 ft wide. At the laying of the foundation stone, the bridge was named Pitt Bridge, after the Tory Prime Minister, but when the bridge was opened in 1769 Pitt was out of favour, and it was renamed Blackfriars Bridge, in honour of the Black Friars who moved their monastery from Holborn to a site near the northern approach road to the bridge in 1274.

Although maintained, the Portland stone was soon eroded by the polluted saline waters of the Thames and the foundations of the bridge became undermined. Much of this pollution was caused by the River Fleet, which flowed into the Thames under a large archway near the western end of the bridge. Over the years it had become an open sewer and it was also a serious health hazard. Repairs were put in hand but in 1840 these were halted in favour of building a new bridge as soon as possible.

Mylne's bridge was demolished in 1860 and a temporary bridge erected in its place. The corporation originally accepted a design by Thomas Page for a three-arch bridge, but at the same time the London Chatham & Dover Railway wanted a railway bridge, and since the railway bridge required five arches, the road bridge had to be amended to five. After two years Joseph Cubbit, was appointed to design both bridges. To overcome tidal scour Cubbit sank massive iron caissons into the river clay and half filled them with concrete. On to these he built up his piers in granite-faced brickwork. The spans, two each of 155 ft and 175 ft on either side of the 185 ft centre are formed of wrought-iron ribs.

From the cutwaters columns of polished red granite were erected to support pulpit-like bays at pavement level. These were embellished by the sculptor J B Philip with sculpted birds and flowers in honour the original Black Friars. On the upstream side these show plants and freshwater birds, while on the downstream side they depict marine vegetation and seagulls. The low cast-iron balustrade completes the 'Venetian-Gothic' effect. The bridge is 923 ft long and 70 wide."