It nearly bankrupted the city. At the dawn of the nineteenth century, Aberdeen's burghers committed to a project that an honest accountant would have called impossible: cut down St Catherine's Hill, vault a deep valley with a single granite arch, and run a perfectly straight new road for a full mile across whatever was in the way. They did it. The Denburn River was buried under the new pavement. A six-storey tenement was hidden under one end of the bridge. Aberdeen called the result Union Street, after the Acts of Union 1800 with Ireland, and spent most of the next century paying off the debt.
Union Street is exactly what it announces itself as: a one-mile boulevard of dressed granite running straight from the medieval Castlegate to Holburn Junction, raised above the older city by a feat of cut-and-fill so audacious it has its own folklore. The Union Bridge, completed in 1805, carries the street across the Denburn Valley on a single granite arch 130 feet across. For decades it held the title of the world's largest single-span granite bridge. The Denburn itself still runs beneath, channelled out of sight, with a dual carriageway laid over it. Charles Abercrombie drew the plans; Provost Thomas Leys and the merchant James Hadden pushed them through the council; the rest of the city held its breath while the bill came due.
Aberdonians call it the Granite Mile, and from any height in clear light you understand why. Buildings on both sides are faced in the local silver-grey granite that gives Aberdeen its other nickname - the Silver City - and after rain they flash and glitter as if mica had been mixed into the stone, which it was. Trams ran down the middle from 1874 until 1958. The grand frontage of the Kirk of St Nicholas faces the street across a small graveyard. Department stores went up; chains came; the Trinity Centre and Bon Accord Centre opened doors onto the pavement. At Christmas, gantries above the road carry strung lights that are switched on with civic ceremony, the same kind the Victorians staged when gas was new.
By 2020, around a fifth of the ground-floor retail units on Union Street stood empty. The pattern is familiar to anyone who has watched a British high street through the last two decades, but it has hit Aberdeen harder than most: oil money receded from the city as the North Sea production declined, and online shopping finished what the recession started. Aberdeen City Council approved a hundred-thousand-pound deep-clean in 2021 to scrub graffiti and repair signs; a study the next year priced full building repairs along the street at eleven million. After thirty-four years of arguments going back to 1986, partial pedestrianisation began in May 2020. Buses returned in July 2022, left again in April 2024, and the central section between Bridge Street and Market Street is being permanently widened for pedestrians and cyclists.
The brilliance of Union Street was always its role as Aberdeen's central nervous system. The road was designed to gather the five great approaches into the city - Queens Road from Hazelhead in the west, George Street from Inverurie and Morayshire in the north-west, King Street from the Bridge of Don and the long road to Peterhead and Fraserburgh, Market Street descending to the fishing town of Torry, and Holburn Street running south. Every road that mattered in north-east Scotland fed into this one mile of granite. Bruce Miller's musical instrument shop, established in 1900, sold pianos and accordions to Aberdonians for 111 years before closing in 2011. The Aberdeen International Street Market still occasionally fills sections of the street with stalls and song. The Granite Mile is bruised, but it is still the spine of the Silver City.
Union Street runs east-west through central Aberdeen at approximately 57.145 degrees north, 2.103 degrees west, between the Castlegate and Holburn Junction. From the air the mile-long straight line of granite buildings is one of the most distinctive man-made features of the city, visible as a pale slash through the otherwise dense urban grain. Aberdeen Dyce Airport (ICAO EGPD) lies about five nautical miles to the north-west. Best viewed at 1500-3000 feet AGL; the Union Bridge across the Denburn Valley is identifiable by the abrupt change of road level visible in raking light.