They are the flaking, weather-worn epitaphs of Scotland's vanishing industries and civilisations.

Hand-painted slogans on the brickwork of buildings were once a common sight in cities, towns and villages across the country, but the explosion of printed billboards in the 1900s led to their decline.

Known as ghost signs, these windows to the past demonstrate a bygone era of craftsmanship and are often left untouched for their historical value and nostalgic appeal.

The intricate signage is commonly found in areas of dense population, industrial significance, or centres of commerce in the Victorian era, particularly in Glasgow, Edinburgh and Dundee.

Producing the giant lettering took time and skill, though labour was fairly cheap, and people often used the same technique that Michelangelo used on the Sistine Chapel ceiling.

Artists would sketch lettering on perforated paper and transfer outlines onto stone using chalk-filled pounce pads, before the delicate painting began - a method still in use today.

Signs often go unnoticed by passers-by, but a growing community across the UK is working to map out and preserve ghost signage before it fades completely from our architectural landscape.

Captivated by the historical slogans, London-based advertising aficionado Sam Roberts founded the Ghost Signs organisation in 2006, in a bid to raise awareness of their value.

"They are often described as being hidden in plain sight," he said. "We're blinded to them in some way, perhaps because the places they were positioned are no longer strategic points for advertising.

"People generally are not paying attention to what is above the first floor of buildings, even more so now because people walking around looking at mobile phones."

Roberts first began to notice ghost signs after moving home, simply because he started walking on a different side of the street.

The 38-year-old now delivers tours around London and has launched an ambitious digital project in building a nationwide ghost sign archive.

Roberts said: "Lots of people talk about process of discovering these things for first time, becoming aware then noticing them everywhere they go.

"Scotland has one very particular style of sign on stone entranceways to buildings that were mixed use, where each stone has detail of one of the occupants.

"Signs for accountants and lawyers were done in very small letters, often using gold leaf techniques. I think that's something that is part of the vernacular of Scotland.

"Red Hackle whisky is my favourite one in Glasgow. You also have whole parts of paint cracking and falling off taking parts of sign with it."

Although now longer in production, Red Hackle is well remembered brew with bottles fetching large sums at auction and miniatures traded by specialist whisky collectors.

The building on Otago Street sports different version of the words Red Hackle painted over one another, with an outline of a whisky bottle vaguely visible on the right.

Outwith advertising, the slogans were also used for significant landmarks and streets, or to remind people of their civic duties.

Here is once such war-time example in Leith, on the corner of Water Street and Queen Charlotte Street.

Above all, it's the stories behind the signs that have sparked interest among people of all ages, according to Roberts.

He hosted a lecture on ghost signs in Glasgow as part of the Merchant City Festival, where people of all ages and professions attended - including historians, advertisers, graphic designers and conservationists.

STV reporter David Cowan is one such enthusiast, who has been documenting nuggets of architectural history across Scotland in a series of montages.

He said: "Ghost signs are a glimpse into our recent history. They come and go. Sometimes they appear when shop fronts are being refurbished and disappear again afterwards.

"When you see a tenement you usually think of them as being homes, not places where people worked, but sometimes at the front doors you can see signs for all sorts of trades and professions - everything from straw hat makers to engravers

"It would take real skill to paint them on to stone walls and bricks, and that's part of the attraction too. They are fading works of art that bring the past to life."