that teaches you to think like an Engineer.

Barcelona is a city characterized by regimental city blocks and wide linear streets.

A departure from the narrow winding streets of most European cities. Yet nestled in these

rigid streets are some of the most unique and beautiful buildings ever created, each

rooted in nature through structural forms and designs.

These beautiful structures stand out among their neighbours, and are the work of one

the world's greatest architects. Antoni Gaudí. His buildings were not just inspired

by nature, they were a celebration of nature. A celebration of life and a celebration of

the God Gaudí devoted his life to.

The Casa Milà, Casa Batlló and perhaps most famously the yet to be finished Sagrada Familia.

All are within a short walk of each other and each is defined by their complex curves

that defied all conventional architectural rules.

These buildings were born from the mind of Antoni Gaudí, born in 1852 to a family of

craftsmen. Antoni Gaudí found much of his inspiration and meaning in architecture by

following the patterns of nature, using the beauty that he saw as a gift of god as the

ultimate blueprint to the world. Guadí himself once said “originality consists of going

back to the origins”, and that he did.

These complex intertwining parabolic forms, created in a time before computers existed.

Are so complex that his magnum opus, the Sagrada Familia, a building which began over 135 years

ago, is still under construction. Today we are going to learn it's story, and why it

has taken generations to complete.

Sagrada Familia began construction in 1882, under the guidance of architect Francisco

De Paula del Villar, who resigned a year later allowing Gaudí to take over at the age of

30. Even at this young age Gaudí saw his opportunity, and set out to make the project

his masterpiece. Transforming the project and incorporating his signature style. Combining

Gothic and Art Nouvelle architecture to create something new.

Sagrada Familia looks like the work of evolution, rather than design. Like a giant elaborate

termite mound, whos blueprint was carved by the laws of nature. Gaudí was not just a

master architect, designing buildings in creative and innovative ways is the challenge of an

artist. He was a master engineer. He understood how these shapes impacted the structural integrity

of the building, and allowed physics and nature to dictate his designs. Rather than fight

against the laws of nature. He worked with them. He bridged art and science like no man

before him, he understood that nature is defined by the laws of mathematics, and to him this

was the ultimate celebration of god.

Columns mimicking trees and skeletons.

Arches mirroring rib cages.

Seashell inspired spiral stairways.

Spires emulating crystals

and ceilings that rival forest canopies for natural beauty. Their designs are all rooted

in natural phenomenon, but for a human mind to recreate them in stone took a man with

true genius.

So how on earth did Antoni Gaudí design something so complex in an era when computational analysis

did not exist. Evolution has happened upon these complicated structures through trial

and error. Natural arches are the work of chance, the weak simply fall before we can

witness them. While plants developed cells capable of sensing the direction of gravity

to influence their growth patterns and bone cells are stimulated to grow and multiple

when placed under stress. Nature is the ultimate form of intelligent design and Gaudi pursued

a simple concept to guide his replication of these designs.

The challenge that Gaudí faced was one of material strengths. His primary building material

being Montjuïc stone, a type of Sandstone. And like all stone it is strongest in compression.

Place a rock in compression and it can withstand enormous pressure, but place it in tension

and tiny imperfections in the rock allow cracks to grow, and soon the entire stone will fracture

along those cracks. The challenge with constructing structures using stone is primarily one of

keeping the stone in compression at all times.

This has been a well known building technique for thousands of years, but it was the Romans

who truly saw and utilised it's potential.

Unlike ancient greek structures characterised by vertical posts and horizontal lintel constructions,

roman buildings are defined by arches and domes. They raised massive structures, like

their famous aqueducts and the Pantheon dome. Structures that still stand today, a testament

to their sturdiness. The arches strength is derived from how it transfers weight to the

ground.

Let's compare a post and lintel structure and an arch spanning an equal distance. As

long as the posts remain vertical, they will remain entirely in compression. The downwards

force of gravity squeezing the stones against the unmoving ground. However, the horizontal

beam, the lintel, will experience both compression and tension as it sags from its own weight.

The upper surface will bend inwards, causing compression, while the lower surface will

experience tension as it is stretched. This severely limits its structural strength. An

arch in comparison allows the force to be distributed neatly across the arch. There

are no hard corners to allow bending stresses to develop. The reaction force from the ground

can travel smoothly up the same path as the force of gravity takes downwards, allowing

the stones to remain in compression, and thus allowing the arch to carry more weight.[1]

This imaginary path is called the line of thrust, and modelling it was Guadí speciality.

Designing with these concepts in mind is relatively simple for a 2D structure like an aqueduct,

but expanding it out to form something as complex as the Sagrada Familia is a whole

other ball game. Even the “simple” columns of the basicalla's interior, split and diverge

like growing trees. The flying buttresses of the passion facade sweep outwards, and

defy belief that they could possibly remain standing when they are constructed from nothing

more than sandstone.

So, how did Gaudí do it?

Simple, he used strings. When you hang a flexible material like a rope over a gap, it has no

rigidity to allow it to remain in any position other than the one that allows it to remain

in pure tension. Hang a rope from a single point and it will hang directly downwards,

the entire length of string in tension. Hang it between two points and it will sag downwards,

until once again the entire string is in tension. Add more weight and it will sag with a deeper

parabolic arch to allow it to remain in tension.

You can see a pattern developing here. We can use strings to map out those lines of

thrust. But we want our stones to be in compression, not tension, how can we apply this to stones.

Simple, take a photo, and turn it upside down.

Gaudi started by drawing footprint of the church on a piece of wood at a 1:10 scale.

Next he attached anchor points for the strings in locations where he wanted support columns

to exist, from there he just gradually started adding strings and weights. The weights were

scaled to represent the actual weight the columns would need to support, at about one

ten-thousandth of the actual weight.

This weight was scaled to represent the difference in stiffness between the string and the rock

that it represented. He tinkered with the string model for a decade before he was content

with its final form. He used this model to inform his design work. In this reconstructed

model underneath the Sagrada Familia, you can see the shape of the building beginning

emerge. This was the skeleton upon which he would carve his masterpiece.

Gaudi devoted the rest of his life carving this model. Designing the intricate facades

each depicting stories from the bible, adding detail that few would see, and as the project

ran on, Gaudí withdrew from life, rejecting any additional projects. In 1914, he made

his home inside the Sagrada Família workshop. His obsession with his final masterpiece took

over his life. He neglected his personal appearance, and became a disheveled recluse. His days

were devoted to praying and overseeing the design and construction of the Sagrada Família.

And on June 7th, 1926. Disaster struck.

At the age 73 in 1926, Guadí was struck by a tram on his daily walk to confession, and

was left to die in the streets. Passersby did not recognise the ragged man as the famous

and beloved architect, mistaking him for a homeless man, he was left to die in the streets.

Hours later Gaudí was taken to the hospital, but received only basic care. When he was

finally recognised it was two late, no more could be done to save his life, and he died

two days later on June 10th, 1926. The funeral that followed, shut down Barcelona streets.

The residents of Barcelona showed up on mass, marching his coffin to its final resting place

in the crypt of the Sagrada Família. The project was less than a quarter complete at

the time of his death.

With the mastermind behind the complex project gone, completing it would become a herculean

task. Made even more difficult by the outbreak of the Spanish Civil War in 1936.

An already difficult task just became the world's most difficult puzzle, as anarchists

destroyed the only existing models of Gaudí designs. Here, the building could have been

abandoned, or it's vision changed. As Spain shook off the cobwebs of post war poverty

in the 1950s, a new generation of engineers and craftsmen devoted their skills to completing

his Gaudi's vision, employing tools and materials that Gaudí never had access to.

Attempts to piece together the shattered models back together were difficult, as pieces were

either too damaged or missing completely. But the designers that took up Gaudi's vision

worked with what they had. This is now their story. This is where this story really begins

to captivate me. This building has taken so long to complete, that it has spanned not

just generations of engineers, but generations of technology.

The passage of time has led to some increases in production rates, but has also caused it's

fair share of delays. Sandstone comes in a wide variety of colours, due to differences

in impurities. These can range from blues and greys right through to pink and red. [3]

When construction began on the Sagrada familia, this sandstone was in plentiful supply from

the Montjuic quarry. Its this stone that gives the Sagrada Familia its distinctive tan colour,

while also having a high quartz content making it more durable than most sedimentary rocks.

But as the decades passed, the stone began to become more scarce. In 1954, when work

began on the passion facade, the limited stock of the stone quickly became apparent. Soon

the sculptor's hands became idle, as the stones availability was limited to whatever was left

over in stocks or what could be scavenged from other buildings in Catalonia. [4]

1000 metres cubed of the stone was made available when the old Olympic Stadium was remodelled

to increase spectator capacity. When stone was not available, they resorted to bricks,

which can be seen in many of the cathedrals towers. But recycled stone was always preferred

when possible. As the project drew on, these sources also began to run dry. Creating a

bottleneck in their supply chain that prevented work from continuing. The project's managers

were forced to start looking for alternative supplies from around the world. Over the past

few decades of construction the cathedral has incorporated various variants of sandstone

and granite. Doing their best to match their colour and physical properties to the original

Montjuic stone. Stone from Galicia, Cantabria, Scotland, England, France have all contributed

to help finish the Sagrada Familia, while other stones have been sourced to meet more

specific aesthetic requirements.

The passage of time has come with plenty of setbacks, but in recent years technology has

provided many blessings. Obvious improvements like modern cranes are noticeable, yet probably

unappreciated by the general public. 3D modelling softwares have slowly caught up with Gaudí's

genius. Early civil engineering software was too simple to recreate his designs, but architects

working on the project discovered that aeronautical engineering design software could model the

complex curves Gaudí envisioned and the project actually resulted in a merging of these softwares

to improve civil engineering modelling techniques. Cash flow has increased drastically over the

years too. For decades the only money the Sagrada Familia received was through donations

to the church, in the early days of construction these donations came in dribs and drabs, but

today the church has no shortage of funding, being one of the most popular tourist sites

in the world. Since it opened its doors to the public, Sagrada Familia has been raising

a consistent and reliable cash flow from the millions of tourists that pay to visit it

every year. Paying for the materials and workers needed to complete it.

But those workers are not always easy to come by. The art of sculpting has slowly withered

away over the past century, and skilled craftsmen are difficult to come by. Here technology

has come in to lend a helping hand.

Sculptures still play an important role in the process, completing delicate tasks like

surface texturing, but today most of the heavy duty cutting is now done by CNC machines,

which can cut the stone exactly to requirements and ensuring perfect fits between pieces and

for the internal steel supports. Because today the workers are not assembling the towers

stone by stone like in Gaudí's time. They are using tensioned steel bars running through

the centre of the stones to compress the stones together and form on larger panel. Allowing

pieces to be partially assembled before being lifted to the tower and assembled like a giant

stone lego set. This has drastically decreased construction time. [5]

With all of these advances the project is now expected to finish far sooner than originally

expected by 2026. On the 100th anniversary of Gaudi's death.

The building has undoubtedly diverged from Gaudi's original designs. The sculptures

of the passion facade are nothing like the sculptures of nativity facade built during

Gaudi's lifetime. Colours of the stone are off in places. The difference in weathering

between the nativity facade and the newer parts is particularly noticeable. The architects

that took up the mantle of Gaudí masterpiece could never have finished it exactly to his

vision after his plans were destroyed, but I have no doubt in my mind that Gaudí would

be proud to see his creation finally coming to a close. Entering the basilica you are

met with floods of colour from the stained glass windows. Each depicting stories of the