A globetrotting dynamic duo have set a remarkable new Guinness World Record - by visiting 20 UNESCO World Heritage Sites in just 24 hours.
Tireless Chris Fletcher, 39, and Adam Leyton, 42, hopped on and off 36 buses, planes and trains as they traversed three countries and 1,200 miles.
The pair from Leeds made whistle-stop visits to iconic spots including Brussels' La Grand-Place, the canals of Amsterdam and the Tower of London.
Business partners Chris and Adam begun their breathless trip at 4am on Thursday at the spectacular Neolithic flint mines in Wallonia, Belgium,
They visited 18 more locations across Belgium, Holland and England before finishing at Blenheim Palace in Oxfordshire at 3am on Friday morning.
The pair then travelled back into London to Guinness World Record HQ to be named official record breakers and be awarded their certificates.
As well as breaking the record for most sites visited in a day, Chris and Adam also claimed the record for most seen in 12 hours, after clocking up 15 in that time.
Speaking hours after the achievement, Adam said: "We are absolutely buzzing to have claimed the record but completely exhausted at the same time.
"I can't wait to get home and collapse into bed."
A World Heritage Site is a landmark or area which is chosen by the United Nations Educational, Scientific and Cultural Organization (UNESCO) as having cultural, historical, scientific or other form of significance, and is legally protected by international treaties.
The sites are judged important to the collective interests of humanity.
Chris and Adam, from Leeds, West Yorks., who co-own a digital marketing agency called CEE Digital, spent a matter of minutes at most sites before hot-footing it to the next.
Chris said: "We were flying through the sites so quickly that unfortunately, it was really hard to stop and enjoy them.
"There were lots of pretty buildings and amazing places that we would have loved to have stayed at for some time and seen but there was no time.
"I think we've both identified a few that we would like to go back to in the future."
The 39-year-old said he would like to revisit the Van Nelle design factory in Rotterdam, known for its beautiful architecture, and Rietveld Schröder House, a home built with creative genius, in Utrecht at a later date.
Adam said the trip went "quite smoothly" for the most part but that things did get hairy within the first hour when the train they were on broke down.
"We thought we were in big trouble and that we'd have to drop a site or two in order to keep our schedule," he said.
"But luckily we were able to claw the time back and get back on track. After that everything went really well."
Two of Adam and Chris' favourite experiences were visiting La Grand-Place, the central square of Brussels, and walking through Westminster in the early hours when it was "completely deserted".
Other sites in Belgium they visited include the boat lifts on the Canal du Centre, mining sites in Wallonia, the town house of architect Victor Horta and luxurious mansion Stoclet House.
They also stopped at the Flemish béguinages - a community for women who gave their lives to God, Plantin-Moretus Museum - a printing museum, Belfries of Belgium and France - a group of 56 historical buildings, and saw the Architectural Work of Franco-Swiss architect Le Corbusier.
In Holland the pair saw the Rietveld Schröderhuis, the cultural landscape of Beemster Polder and the defence Line of Amsterdam.
After flying between the Dutch capital and Heathrow Chris and Adam went straight to Kew Gardens before heading into the city centre.
There they saw the Cutty Sark, the Tower of London and Westminster before finishing at monumental country house Blenheim Palace.
Almost exactly a year ago Chris and Adam set the world record for most cities visited in a day by stopping off at seven between London and Budapest.
In order to get their records authorised the pair had to provide Guinness World Record officials with evidence including tickets, GPS tracking and witness statements.
Chris and Adam are expected to embark on yet another record-breaking journey next year, although they're not ready to reveal their plans quite yet.