There's been plenty written about the world's tallest and oldest buildings. But what about the longest?
Excluding walls and fortifications (otherwise the Great Wall of China, at 8.8 million metres, would win by a landslide), Britain once possessed the record holder.
Netley Hospital, founded in 1856 in response to the Crimean War, was England's largest building and, several sources suggest, the world's longest at the time of its completion.
Standing guard over the shores of Southampton Water, it stretched for almost 450 metres and, with its cupolas, towers and pillared porticos, was undeniably beautiful from the outside.
What went on within was rather less so. Netley served as a military hospital, or "palace of pain", where wounded soldiers recuperated after taking part in campaigns in the various corners of the British Empire.
Queen Victoria was a regular visitor, hopping over from Osborne House on board the royal yacht with scarves and shawls for the troops knitted by her own hands.
It was particularly busy during in the First World War, when its 138 wards were inundated with the shell-shocked survivors from the trenches. Some 30,000 patients arrived in the weeks following the Battle of the Somme.
Its architectural might was only skin deep. While vast and visually attractive it was not practical. Corridors, for example, were on the sea-facing side of the building, while the wards faced an inner courtyard - which meant conditions for patients were dark and stifling. "To the naked eye it is a triumph of modern architecture, but should you inherit the misfortune to be sectioned there, one would not think of the place as so," was the verdict of one 19th century journalist. For a vivid account of life there during the First World War, read The Dust that Falls from Dreams by Louis de Bernieres.
Netley was used during the Second World War too, but fell into disrepair soon after. A large fire caused significant damage in 1963 and the whole building - bar the hospital chapel (which is usually open to visitors but currently closed for refurbishment) - was bulldozed in 1966.
By this time, however, it was no longer the world's longest building. That title (again, excluding fortifications) was seized by a vast German structure in the 1930s. Mercedes factory? Airport? Nope. Nazi beach resort. And it is still standing.
Prora, built on the island of Rugen between 1936 and 1939, consists of several identical connected six-storey buildings. Added up, they measure 4500 metres. That's a lot of linen and sun loungers.
Butlin's was the inspiration. Robert Ley, head of the German Labour Front, aware of the UK company's business model, envisaged Prora as a means to provide affordable holidays for the ordinary worker. The Nazi's Strength Through Joy programme, essentially a state-funded travel operator (with free brain-washing service), sent 1.7 million people on a package holiday in 1937 alone (plus millions more on weekend trips and organised hikes). Prora, built in part by forced labour, would have helped boost that number even further.
Designed by Clemens Klotz, under the guidance of Albert Speer, it would have housed up to 20,000 holidaymakers. Each room would have faced the sea, measured five metres by 2.5 metres, had two beds, a wardrobe and a sink. There was also talk of a giant festival hall, two swimming pools, a cinema, a theatre and a dock for passenger ships.
The onset of war put paid to those plans and from 1945 until 1955 the building served instead as a Soviet military base. In 1956 Prora became a restricted East German military area, used for top secret urban combat training.
After reunification its demolition was mooted, but - following a decision to give it protected status - it became a military technical school and was then used to house asylum seekers.
Following decades of failed attempts to flog the building in its entirety, the various blocks were slowly sold off one by one to property developers – with the goal of finally bringing sunseekers to this picturesque stretch of Rugen's coast.
Prora Solitaire, one of the biggest new developments on the site, opened in 2016. Described as a "holiday paradise" in "one of the largest historic buildings in Germany", its apartments can be booked on websites such as Airbnb.
Prora Platinum is another. It claims to have turned a "world famous monument" into a luxurious "symphony of perfection".
For more affordable stays, there's the DJH Youth Hostel Prora. The website HostelWorld sells beds and makes guarded reference to its "eventful past".
But the renaissance of Prora has caused plenty of consternation. "This is a place where 20,000 people were to be groomed to work and wage war," Katja Lucke, chief historian at a private museum at the site, told AFP in 2016. "Of course people see this gigantic complex and are fascinated by it. But you cannot afford to make it banal. You have to put it in context."
So would you stay at Prora?
Despite its controversial history, many would appear to have no qualms with staying at the Baltic resort. There are dozens of - mostly glowing - reviews on Booking.com and TripAdvisor for apartments on the Prora complex.
And Rügen is undoubtedly lovely: laid-back, eccentric, old-fashioned, and perfect for people who like the seaside but not the wilting heat of the Med. A bit like Britain, really. Indeed, the wider Meck-Pomm region, of which Rügen is part, was recently described by John Gimlette, writing for London's Telegraph, as Germany's answer to Norfolk.
Of Rügen, he wrote: "Out of season, you may have some of the great sweeps of sand to the south all to yourself. But be warned: in August, it can get crowded. Germans love it here, and, for over a century, resorts like Binz [which lies just to the south of Prora] have been lavished with mansions and spas. Recently, it's all been restored, a glorious feast of Poseidons and columns, and – once again – there's a glossy black steam train tootling through town."
The Telegraph, London