The unique island in front of the NIA is now generally known as Old Turn, however Deep Cutting Junction is more accurate. It dates from World War Two and the direction sign was installed by the BCN Society in 1983. Going under Tindall Bridge and past the old Toll House, you start to descend 81ft through the Farmer's Bridge Locks or 'the old thirteen' with Cambrian Wharf and the former Newhall Branch to the right. The Islington Place Footbridge is a contemporary antidote to all the Horseley style bridges that you've seen and, as you skirt the Jewellery Quarter, instead of factories, the canal is overshadowed now by modern apartments and office buildings. Saturday Bridge, where the story goes that boatmen used to get paid on that day of the week, is between locks 4 and 5. 

Between locks 8 and 9 you'll go over Whitmore's Arm (c.1810), a private canal that served local sand pits, William Whitmore's foundry and later several factories including Elkington's, once the world's largest metalworking factory that stood on both sides of the canal and specialized in electro-plating. The company were responsible for both the men's and women's Wimbledon tennis trophies that are still played for today and more jewellery is still produced in the immediate area than anywhere else in the country. The nearby Birmingham Assay Office, set up at the insistence of Matthew Boulton, is the busiest in Europe. 

Tourists, and walkers of a nervous disposition may baulk at the cramped tow path under Newhall Street, especially as the canal then disappears under Brindley House, a luxury apartment block built on stilts. After becoming slightly less claustrophobic, you then plunge into the heart of darkness that is the huge unlit cavern below the railway lines going into Snow Hill Station. Emerging into daylight with signs welcoming you to the Second City at the bottom lock, the not unpleasant landscape until Newtown Row consists of old factories and remnants of the many wharfs that once lined the canal plus groups of friendly drunks and the occasional angler. 

Aston Junction, from where the Digbeth Branch Canal departs to Warwick Bar and the Grand Union, is the first piece of greenery you'll see since the City Centre. The Aston flight of locks drop the canal by another 70ft. and for some time it seems as if the world has turned its back on the canal. However, as the Lock Cottage at Thimble Mill Lane is approached, you'll see that even bluebells can flourish here in the spring. 

The canal now has a more open aspect but you wouldn't call it pretty as you continue over a succession of disused wharfs and arms until Cuckoo Wharf moorings with Salford, and above it Spaghetti, Junction looming in the distance. There was for eighteen months during 1919 -1920 a passenger service for Fort Dunlop workers along this stretch, with five heated and lit fly boats carrying 5000 people a week from Holborn Hill. 

Salford Junction was the home of renowned carriers T & S Element who in the 1930s and 40s operated as many as 200 craft. The main commodity was coal from local collieries to factories on the BCN, one of their major contracts was carrying coal from Pooley Hall Colliery near Polesworth to the huge GEC factory at Witton, see Tame Valley canal walk but by the 1970s their fleet had been reduced to six carrying factory rubbish. There was also fuel merchants and boatbuilders Spencer, Abott & Co., established in 1913 by Howard Spencer, a player in Aston Villa's golden era nicknamed 'The Prince of Full Backs' who later became a director of the club. 

Bearing right at the junction to follow Tyburn Road, you'll find yourself with canal on one side, refuse strewn River Tame on the other and a motorway overhead. Soon after these delights there's a large electricity sub-station, there was also once a basin here dating from the 1860s where dried sewage from the nearby sewage farm was loaded onto boats. You then disappear under the old BIRLEC factory which was extended over the canal in the late 1930s. Established in 1927, they manufactured industrial electric furnaces. Erdington Hall Bridge is then reached which takes its name from the local 17th century manor house that was demolished in 1912 to make way for the construction of the Tyburn Road. 

Believe it or not the canal becomes a lot greener but largely uninspiring as you pass more scrapyards. There's even a neat little housing estate which is predictably followed by a monolithic, nameless warehouse. Approaching Tyburn Bridge, look to the right and there's the famous Fort Dunlop and the Jaguar factory that was the main manufacturing plant for Spitfires during the war, with an impressive memorial on the adjacent Spitfire Island designed by the grandson of local lad JRR Tolkein. 

Walking parallel to the busy Kingsbury Road, Minworth Top Lock is soon reached and the site of the former Cincinnati factory, now a housing estate, and the site of its eponymous bridge which was demolished in 2017. Nothing particularly of note now happens but the outlook improves with smart canal side houses and willows weeping into the water until the Boat Inn and a refreshing libation just before the city boundary.