Imagine the world's most fascinating buildings and wonders like Barcelona's Sagrada Familia and Bavaria's Neuschwanstein Castle probably spring to mind. While you might think these man-made feats look pretty much perfect, they're actually not quite complete. From cathedrals and temples to fairy-tale fortresses, we reveal the amazing world landmarks that have never been finished.

Not far from the world-famous presidential faces of Mount Rushmore, another enormous effigy looks out from the Black Hills. This is the face of Crazy Horse, an indigenous Lakota warrior known for his pivotal role as a leader during the Great Sioux War of 1876-77. The colossal mountain carving was the vision of Chief Henry Standing Bear, a Lakota chief and the cousin of Crazy Horse, who wanted to immortalise his late, great relative in the sacred Black Hills. He enlisted the help of sculptor Korczak Ziolkowski, pictured here with the tree-trunk-carved model he used for the project.

The first blast of Thunderhead Mountain, where the statue is located, happened in 1948. Korczak had decided that the tribute should take over the whole mountain meaning that, upon its completion, it would stand at a whopping 563 feet (172m). Work continued steadily through the 20th century (persisting after Korczak’s sudden death in 1982) and 50 years after the initial blast, in 1998, Crazy Horse’s face was completed. The sheer enormity of the task means there’s still much to be done.

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The Hassan Tower, in Morocco’s capital, was an ambitious project dreamt up in the 12th century by Caliph Abu Yusuf Yaqub al-Mansur, who ruled from 1184–99. The caliph was well known for his grandiose building plans and this Rabat tower was to be the mother of them all. It was intended to be part of a titanic mosque – the largest in the world in fact – and it would be the biggest minaret on the planet too. Building began in 1195.

However, when Caliph Abu Yusuf Yaqub al-Mansur died in 1199, work on the mosque and its mighty minaret stopped and construction was never resumed again. The Hassan Tower still stands in its half-competed state today, having reached a height of 140 feet (43m), about half its planned size. The foundations of the unfinished mosque are visible on the site too.

This half-finished landmark might look more at home perched on a craggy outcrop in Athens, but it actually sits atop Edinburgh’s Calton Hill. Envisaged as a tribute to fallen Scottish fighters in the Napoleonic Wars, the monument was to be an exact replica of the Parthenon, the ancient temple that forms part of the Acropolis. Funds were raised in the early 1820s by a group of Edinburgh’s wealthy elites and ground broke in the same decade. The structure is pictured here circa 1881.

However, the project planners failed to collect enough money to complete the monument and tools were downed by 1829. When work finished, only 12 columns – the 12 still standing sentry on Calton Hill – had been erected. Over the decades, many ideas for how to use and/or complete the monument have been floated, but so far nothing has stuck. This little slice of Greece remains today.

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Standing head and shoulders above the rest of Pyongyang’s skyscrapers, this gigantic pyramidal structure has been a work in progress for decades. Ground first broke in 1987 and the building was intended to be a 3,000-room hotel with bells and whistles such as revolving restaurants. However, its construction has been plagued with issues – so much so that the landmark has been nicknamed the “Hotel of Doom”.

Early engineering problems slowed initial progress, then North Korea was plunged into a period of economic crisis after the Soviet Union's collapse. Construction was halted in 1992 and it stood a mere shadow of its blueprint – a hollow shell without windows or any interior fixtures. Work wouldn’t resume until 2008 when Egyptian firm Orascom restarted construction. Today it’s clad in glass and illuminated with LED lights, but remains closed.

This Big Apple cathedral may look mighty impressive today but it’s actually still not finished. The idea for a huge episcopal cathedral in New York City was first floated in the 1820s but, for economic reasons, the cornerstone of St. John the Divine wouldn’t be laid until 1892. From then on, building was in full swing, with services held in a chapel of the crypt as early as 1899. It’s pictured here in the continued throes of construction in 1927.

The Second World War halted construction and work wasn’t resumed until the 1970s. In the 1990s, a lack of funds put a stop to plans to complete the lofty south tower, then a fire in the early 2000s damaged other parts of the church too. After this, post-fire restorations were completed and other construction work was carried out in fits and starts. Today it remains unfinished, with features from the original design including towers yet to be completed. Even so, it’s still the largest cathedral in the United States and a designated New York City Landmark.

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Right in the heart of Myanmar is the tiny town of Mingun and its star attraction, the Mingun Pahtodawgyi, a hulking stupa commissioned by King Bodawpaya in the late 18th century. If completed as planned, the monument would have been the largest of its kind in the world – but it stopped around two-thirds short of its 490-foot (149m) blueprint. The king used forced labour to construct his vision and the project unsurprisingly proved unpopular with locals at the time.

It’s widely believed that the king’s superstition stopped the stupa’s construction in its tracks. During building work, it was prophesied that, upon the completion of the monument, the king would die – wary King Bodawpaya is thought to have decelerated progress as a result. When he did eventually die, the project was halted altogether and it was ultimately left to ruin. The mighty crack that can be seen today was the result of a 19th-century earthquake.

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Smouldering on a Toronto hilltop, this early 20th-century castle could have been plucked straight from Europe. Indeed, the man who spearheaded its construction – wealthy Canadian financier Sir Henry Pellatt – was inspired by his travels on the Continent as a teenager. He plunged his fortune into building the 98-room castle, moving into the sumptuous pile himself. It’s pictured here under construction circa 1912.

Sadly, Pellatt’s economic situation took a turn for the worse. Buried under mountains of debt, Pellatt sold his many treasures, including his palace, and moved from the premises. When he left, areas of the castle were still left unfinished. The third floor was never completed and today the shell is used to house a museum: the Queen's Own Rifles of Canada Regimental Museum.

One of the world’s most awe-inspiring ancient wonders, the Great Sphinx, part of the Giza pyramid complex, is shrouded in mystery. Constructed with the head of a man (thought to be then-ruler King Khafre) and the body of a lion, the Sphinx stretches out for 240 feet (73m) and rises to 66 feet (20m). Despite its great bulk, some experts believe that the Great Sphinx, photographed here buried in sand circa the 1870s, was never actually finished.

In the 1970s, archaeologists found several items at the Sphinx site that suggest builders of the ancient monument left before it was completed. These included abandoned stone blocks and the remnants of what’s thought to be a worker’s lunch and stone hammers. There were also partially quarried swathes of bedrock, giving the impression that labourers simply downed tools and left before the job was done. Still, the monument they left behind looks pretty impressive to us.

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Not to be confused with Westminster Abbey, Westminster Cathedral is a vast Roman Catholic church with a striking striped-brick facade and an interior decorated with mosaics. From the outside, you’d never know that this sacred building in London isn’t finished. But, inside, there are portions of the cathedral’s famed mosaics that aren’t quite complete.

The interior mosaics were envisioned by the cathedral’s architect, John Francis Bentley, an ecclesiastical specialist who began constructing the landmark in 1895. However, he died in 1902, before its completion, leaving behind no finished mosaic works in the cathedral, and just a smattering of pencil sketches and written intentions. The job fell to other architects and designers, and work to finish the masterpiece continued throughout the century to this day.

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A stone’s throw from the famous Angkor Wat, Tao Keo, also within the ancient city of Angkor, is a somewhat humbler temple. Built under the Khmer Empire around the start of the 11th century, it’s enveloped in greenery, just like its famous sister, and comprises five towers and a stepped pyramid. But, unlike Angkor Wat, it lacks the ornamental decoration Khmer buildings are renowned for and, most importantly, was never finished.

It’s not known for sure why the temple wasn’t completed. Work may have been halted upon the death of Angkor king Jayavarman V, for whom the temple was built. It was also apparently struck by lightning which could have led locals to believe the temple was cursed. Today the stark, stepped temple stands out among its highly decorated neighbours.

This opulent Neo-classical palace can be found within the limits of the Portuguese capital. It was predominantly built in the first half of the 19th century and was a replacement for an earlier royal palace, which had been demolished by fire. However, a series of obstacles – from economic woes to political turmoil – meant that the glittering Ajuda National Palace was fated never to be finished.

The unfinished palace was abandoned dramatically when it was invaded by Napoleonic soldiers in 1807, forcing the royal family to flee for their lives. Work eventually picked up again but was stopped once more in the early 20th century, as the Kingdom of Portugal was overthrown in 1910 (giving way for the modern Portuguese Republic). The western wing of the palace (pictured) was never completed but other parts of the palace serve as a public museum.

The tale of this dramatic castle in New York’s Alexandria Bay is ultimately bound up with a love story. It was built for wealthy hotelier George C. Boldt, who intended it as an extravagant gift for his beloved wife, Louise. The family indeed passed several happy summers in their unfinished island castle until 1904, when Boldt’s world came tumbling down. Louise died suddenly and Boldt ordered that construction be stopped indefinitely and he never returned to the island.

The castle remained abandoned and battered by the elements for decades, until it was eventually overtaken by the Thousand Islands Bridge Authority in the 1970s. Today the castle’s exterior gives little clue that the building isn’t quite complete, but inside visitors can usually still see the unfinished rooms. This photo shows a snapshot of the unfinished third floor – work on the basement was never wrapped up either.

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The striking arches of Bara Kaman spread out in the north of Karnataka state in southwest India, and form part of the mausoleum built for ruler Ali Adil Shah II in the 17th century. The king was just a teenager when he ascended to the throne and he had his heart set on a mausoleum that would outshine all others. However, his dream was never fully realised. This archive snap shows the landmark as it was in the 1870s.

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The mausoleum of Ali Adil Shah II was never completed and no one really knows why. Some say it was because the young ruler’s mighty mausoleum may have cast a shadow (literally) over Gol Gombaz, the mausoleum of king Muhammad Adil Shah, his father and predecessor. Either way, the unfinished site was still the burial place of the late king and remains a tourist attraction in its own right.

The ultimate in Disney-esque European castles, Neuschwanstein sits high in the hills of Germany’s leafy Bavaria region. It was the vision of King Ludwig II, a 19th-century ruler who was inspired by medieval fortresses. All turrets and towers, it was – and remains – a grandiose feat of engineering, but one that King Ludwig would sadly never see completed.

The king moved in before his beloved castle was even completed, but was only able to enjoy it for 172 days. He died in 1886, leaving behind his incomplete fortress. After his death, many of the king’s elaborate plans for the castle were abandoned but several areas were quickly finished in order to welcome the paying public. Even today many of the rooms remain unfinished and off limits to visitors.

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Lauded architect Antoni Gaudí sprinkled the Catalan capital with landmarks, and no feat of his is more impressive or famous than the Sagrada Familia. Despite its international stardom, Gaudí’s basilica – with its flying buttresses and soaring huddle of spires – is still not complete. Work on the landmark began in 1882 (originally under the watch of Spanish architect Francisco de Paula del Villar) and it’s pictured here, unfinished some 60 years later, circa 1940.

Gaudí took the reins in 1883, breathing ambitious new life into Villar’s plans. Then, from 1914, the great architect worked exclusively on the cathedral, overseeing the building of a lofty bell tower and the crypt among other features. However, progress dwindled after Gaudí’s death in 1926. Parts of the basilica were damaged during the Spanish Civil War and local opponents of the building slowed momentum even more. Today, the project still crawls towards completion, but its unfinished state doesn’t deter the millions of visitors who typically descend each year.

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