A very ancient bridged crossing at Perth had certainly existed since the 13th century. It is mentioned in a Scone Charter of 1219. The city was the effective capital of Scotland, the royal residence for long periods and the seat of many Scottish parliaments. It was at the lowest crossing point on the Tay. In the 12th century it was the richest trading city in the country. The river was navigable and the harbour was adjacent to the High St. The bridge was also here. It existed for 400 years, until the last one was swept away by floods in 1621. Then, for 150 years there was no bridge and it was not finally replaced until the later eighteenth century. A bridge appears on Pont’s maps of 1600 but not on Roy in 1750. Pont’s bridge is 200m downstream of the present bridge, effectively extending across the river from the High St.
The city had always been vulnerable to floods and has a very unhappy history with respect to bridges. Four have existed prior to the one that exists today. All have been destroyed or fatally damaged by floodwaters. The first recorded storm was in 1210. Several sources report enormous floods and many people drowned. Perth Castle, the royal residence, was destroyed and some of the King’s family were lost. The bridge was washed away. Four years later it had been rebuilt, as we know that William the Lion had died and that the new King Alexander met his father’s funeral cortege at the bridge. First government records are for for maintenance payments in 1303. In 1317 it was mentioned in a charter of Robert the Bruce, and in 1328 the King asked the Abbot of Scone to allow stones to be taken from Kincarrathie Quarry for repairs to the Bridge of Perth and to the Bridge of Earn.
The Exchequer Rolls record a payment in 1391: “Pro Construccionibus” as opposed to the more usual “ Ad Fabricam”. This suggests that a third bridge was being built, presumably in the wake of more flooding. In 1405 Exchequer Rolls stipulated that an annuity was to be provided by Robert III for masonry costs over the ensuing 150 years. Regular payments are seen in these documents, through the 15th century, for £10/14s/8p …. ad sustentacionem pontis de Tay . A John of Pelis acquired payments for work on the Tay Bridge at Perth in 1464 and 1487.
In 1515 a Robert Merlion was hired as master mason at the Tay Bridge rebuilding. He in turn employed two other family members: a John and an Andrew Merlioun. While under construction, two more masons, Thomas Fotheringham and John Brown of Dundee were called in as consultants. It was built with eight arches but nothing more is known. Perth OSA reports a note that in 1566 “ the brig haiffng twyst fallin doun and decayit and laitlie being erectit of tymmer is ready to fall without present help”. Three arches collapsed in 1573, and despite these being repaired, five arches collapsed in 1589. Interim repairs were possible however, and the fifth bridge was not started until 1604. James VI engaged his own Master Mason, John Mylne. to build this bridge a little to the north of the old site. It took 12 years to build because of dreadful weather. Although it was completed in 1616, it was poorly designed and lasted only five years. It was reputed to have 11 arches. An unidentified bridge on one of Timothy Pont’s manuscripts shows an 11 arched bridge which may well be this one at Perth. In 1621 another storm washed it away: “ Hailly hung doun excepting only one bow thereof standing”. The floods lasted three days and also made many homeless as well as destroying the town's stores of meal and flour. Many had gathered in the St. Johns Kirk to survive the deluge.
It appears that the citizens of the town now threw in the towel for there was no further bridge building over the next 150years. River-crossing was by ferries and as many as thirty boats plied their trade across the fast flowing river. During this period many ferrymen lost their lives, as did many of their clients. Trade in Perth declined. It was during this time that William Roy's survey was conducted.
Thomas Hay, 9th Earl of Kinnoull, was the proposer of the next bridge which still exists today. A 1765 Act of Parliament sanctioned its construction, commissioners were appointed and funds raised. The government contribution came from forfeited Jacobite estates. John Smeaton, famous for the Eddystone lighthouse, was appointed chief architect. He already had been appointed to the Forth and Clyde Canal and was to become one of the fathers of British civil engineering. Work began on an experimental pier near the east bank using a cofferdam, and then progressed to all the piers by 1768. The arches were completed in 1771. A halfpenny toll was to be charged. The bridge had cost £26,446.
In 1773 sheet ice, followed by massive floods, presented its first challenge. Flood waters destroyed the quays and walls on the North Shore and flood water rushed down the High St. But the bridge held.
It was widened in 1869, with cast-iron footwalks, and was later to carry trams; at first these were horse-drawn but later ran on electricity .
Today Smeaton’s 1771 bridge has nine dressed pink sandstone arches, all segmental except for the most northerly one which is a small semicircular. Two of the arches are on land, serving as flood arches. The spans increase towards the centre arches of 75ft. The spandrels are rubble built and the abutments are in pink sandstone. Cast iron walkways are on each side. Circular oculi infilled with whinstone decorate each of the spandrels. It is 893 ft long. The most innovative attribute cannot be seen; this is the first bridge to have been built using parallel wall type spandrels incorporating closed-in voids to lessen their weight. According to a commentator, "these were not the most daring of Smeaton's innovations in bridge construction, but they were certainly the most successful".