To qualify, Harlech had to prove that the street is a main thoroughfare commonly used by the public, fully surfaced and with buildings along it.
Harlech in Wales, previously known for its 13th-century castle, now has another claim to fame. The small coastal town was certified by Guinness World Records on Tuesday as having the world's steepest street.
Ffordd Pen Llech has a gradient of 37.5%, which means that "those travelling on the street go 1 metre up (or down) for every 2.67 metres travelled horizontally," Guinness World Records wrote.
It beats the previous record-holder, Baldwin Street in New Zealand's Dunedin, which has a gradient of 35%.
Harlech resident Gwyn Headley, who campaigned for the street to be verified after hearing of Baldwin Street's record, said: "I cannot say how pleased we are that Ffordd Pen Llech has now been recognised as the steepest street, not just in Wales, not just in the UK, not just in Europe, but in the entire world."
Fellow resident Sarah Badham, who helped run the Facebook page for the campaign, added: "It's amazing."
"As somebody who was born and raised here, I can't really say how special it is," she said.
'First the cricket, now this'
To qualify for the title, Harlech had to prove that the street is a main thoroughfare commonly used by the public, fully surfaced and with buildings along it.
It was excused for not presenting blueprints older than 1842 as the street is believed to have existed for more than 1,000 years.
Craig Glenday, the editor in chief of Guinness World Records, congratulated the residents for their campaign to bring the title home.
"The local community in Harlech has shown sheer will-power in their quest to earn Ffordd Pen Llech the title," he said.
"I hope Harlech enjoys the celebrations and that the new title brings lots of people to the beautiful town, to experience the world's steepest street for themselves," he added.
Dunedin lamented the loss of its title, which came hours after it narrowly lost the cricket World Cup final.
"First the cricket, now this...," Dunedin said on its Facebook page.
But it said Baldwin Street remained a must-do attraction "and a shoo-in for the most popular steepest street award judging by the thousands of quirky and creative photos taken over the years."