Prized by antique dealers, revered by history buffs, but an object of puzzlement to many a 21st century pedestrian, the humble boot-scraper is back in the spotlight in its favoured home, Belgium.
Known as a "decrottoir" in French, which taken literally implies the need to remove excrement, the cast-iron contraptions feature in London, New York and other major world cities but abound in Belgium's 18th and 19th century streets.
Nowhere is the implement crafted to scrape mud off shoes more visible than in this country, according to academics from the Free University of Brussels, or Universite Libre de Belgique.
"Boot-scrapers were born at the same time as footpaths. This mundane contraption from daily life is a key to urban history," ULB history professor Christian Loir told AFP.
"It is part of the history of walking in our cities."
Set in semi-circular niches beside the front doors of most homes, the ground-level scrapers have long fascinated the tens of thousands of expats sent to Brussels each year to work at the many EU-linked institutions and diplomatic missions.
"I like to tell children they are the front doors of the house gnomes," said a blogger.
"I?ve become a little obsessed with these contraptions, pointing out the prettiest whenever I?m strolling along the cobblestone footpaths of Brussels," wrote another.
Brussels' biggest university recently focused on the early version of today's doormat at a world forum on the history of walking and urban space, and a central city exhibition is highlighting the almost 1,000 different models found on city streets today.
Professor Laurence Rosier, who teaches at the ULB and curated the show, said the scrapers were a testimonial to the stonemasons and ironworkers of yesteryear as well as to the invention of the contemporary footpath.
Though the ancient Romans built footpaths, only the poor walked Europe's cities until the late 18th century when the bling classes of the time hopped off their carriages to amble the streets.
"Walking suddenly became fashionable," said Loir. "This was a key moment in urban history, when the elite discovered the city. The impact was enormous."
The sudden popularity of walking the streets helped shape today's cities, with footpaths, tree-lined boulevards, public parks and covered arcades built during the 19th century.
"Suddenly there was a new quality to public space," Loir said.
The new taste for strolling also saw shoes morph from heavy high-heeled designs for indoors to softer, low-heeled, foot-fitting gear, as scientists engrossed themselves in the study of motor skills and local authorities turned to public hygiene, improving sewerage and offering public toilets.
In the first decades of the century, footpaths were lined with scrapers to wipe off the mud and excrement before going indoors. As more and more people adopted the walking habit, it became vital to clear a special space for the new pedestrian class, safe from the flying mud and bolting horses.
In the 1840s, scrapers were ordered off the street as authorities in Belgium removed all obstructions in the interests of public safety.
Instead, the ubiquitous "decrottoir" was now fixed to houses, by the front door, leading to a change in social habits such as removing one's shoes on going inside.
"There were manuals published on how to enter a home, how to be civil by not taking off one's shoes, and huge catalogues on manufacturers" of boot-scrapers, said Rosier, who with photographer Christophe Holemans spent several years researching the subject before the summer show.