In the early 15th century, there
was a competition to design the bronze doors for the Baptistery of San
Giovanni in Florence. The two main competitors were Filippo Brunelleschi
and Lorenzo Ghiberti. Their panels both depicted the biblical story of
Abraham preparing to sacrifice his son, Isaac. The panel by Brunelleschi has a
more rigid composition with figures that appear less three-dimensional. It
emphasizes the narrative of the scene, making it easy to follow, but it does
not incorporate the depth and perspective that would later become central to
Renaissance art.
Ghiberti’s
panel is more intricate, with greater attention to perspective and the
arrangement of figures in space. His use of foreshortening, a technique
that makes objects appear to recede into the background, gives his panel a more
lifelike quality. Some of the details in his work, however, make the scene more
difficult to interpret at first glance.
Art
historians generally agree that Ghiberti won the competition. However, some
sources suggest that the judges originally declared a tie and asked both
artists to collaborate. According to some accounts, Brunelleschi refused to
work together and withdrew, leaving Ghiberti to complete the commission.
Brunelleschi
later shifted his focus to architecture. He played a major role in the
completion of Santa Maria del Fiore, commonly known as Florence
Cathedral. The cathedral had been under construction since the late 13th
century, with several architects contributing to its design. The campanile
(bell tower) was designed by Giotto di Bondone in the 14th century.
One of the main challenges in finishing the cathedral
was constructing the dome. The space left for the dome was large, and there was
no clear solution at the time for how to build it without the use of
traditional wooden centering, which would have been difficult given the scale.
Brunelleschi, working between 1420 and 1436, developed an innovative method
that allowed the dome to be built using a herringbone brick pattern and a
system of interlocking ribs for support. His approach allowed the dome to be
constructed without external scaffolding, making it one of the most significant
engineering achievements of the period.
During
the Renaissance, new wealth led to increased interest in construction projects,
but many patrons wanted to see results within their lifetimes. Instead of
commissioning entire cathedrals, they often funded smaller chapels or
decorative elements that could be completed more quickly. An example of this is
Giotto’s work in the Scrovegni Chapel.
The
Medici family, however, took a different approach. They supported the
completion of Florence Cathedral and ensured that a dome would be built.
The overall design of the cathedral follows a Romanesque layout, but the
structural details vary. The vaulting inside is Gothic, featuring ribbed
groin vaults. The dome itself belongs to the Renaissance period. The
building’s exterior was completed later, and the facade was redone in the 19th
century. The design of the facade has elements that resemble Byzantine architecture.
The
front of the cathedral has decorative patterns that resemble the exterior of
the Baptistery of Pisa. The design creates a layered effect, possibly an
intentional reference to architectural styles from the 13th century and earlier
Byzantine periods. Inside, the pointed arches and rib vaults define the
space. The cathedral has two side aisles with pointed arches, which are also
used at the far end of the building. The structural details and materials
reflect different architectural influences, with the interior being primarily Gothic.
The area where the transept meets the nave
creates a large open space at the crossing of Florence Cathedral.
Brunelleschi was tasked with solving the structural challenge of completing the
dome. The cathedral follows a Latin cross plan, and the original design
intended for the dome to be a perfect circle, similar to the Pantheon in
Rome. Instead, Brunelleschi created an octagonal design, dividing it
into segments to improve stability. The shape made the structure stronger and
allowed it to be built without traditional wooden centering, which was
difficult for a dome of this scale.
Brunelleschi had traveled to Rome, where he studied
ancient architecture, including the Pantheon. He made sketches and
analyzed classical structures, but the final design of the cathedral’s dome
does not replicate the Pantheon’s form. When presenting his idea to
Florence’s leadership, including members of the Medici family, he was
asked for a model or working plans. Instead, he demonstrated his concept by
standing an egg upright, supposedly cracking the shell to show how a vertical
structure could support itself.
The
dome is not a perfect hemisphere but has an ovoid shape, giving it a
slightly elongated form. It is divided into eight segments and includes
a unique system of double walls. Between the inner and outer walls,
Brunelleschi designed an interlocking brick pattern that helped distribute weight evenly. To further support
the structure, he incorporated exterior buttressing, including small
domes surrounding the base of the main dome. A lantern was later added
on top, completing the design.
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If you look at the cutaway of the
dome, you can see that it has a double-dome construction. A similar idea
was used in the cathedral at Pisa, where a rounded dome was combined
with a more pointed one, giving the structure a shape that some have compared
to a bottle. In this case, Brunelleschi designed a system of ribs that
functioned almost like layers in a laminate countertop. By overlapping
wooden beams and using their tensile strength to oppose forces, he
created a structure where the ribs pushed outward from the center. This outward
force gave the dome a degree of flexibility, which was important in a region
like Italy, where earthquakes and shifting ground could pose a problem for
large buildings.
Along
with these structural ribs, Brunelleschi built an outer dome that enclosed
another, slightly more vertical dome inside. He also used a herringbone
pattern for the masonry, laying the bricks in an interlocking arrangement that
spiraled upward. Laying the bricks this way was difficult, and working at that
height added to the challenge. Workers stood on wooden planks attached to
temporary platforms, and at times, even Brunelleschi was unsure if the method
would succeed.
Instead of using the traditional scaffolding
method found in Gothic cathedrals, where bricks were placed on top of a
temporary wooden structure, he had to develop a new way to support the bricks
as they were laid. Unlike the Pantheon, which may have been filled with
sand and had scaffolding built around it, Brunelleschi left the interior space
open as the dome was constructed.
Because
the double-dome construction created forces that pushed outward,
Brunelleschi needed a way to counterbalance them. To do this, he designed a lantern
at the top, a structure that looks similar to a miniature Gothic spire.
The weight of the lantern pushed down on the oculus at the center of the
dome, helping to keep everything stable.
To support the lantern placed on top of the
dome, Brunelleschi added a series of smaller domes around the base. These
structures acted like bookends, pressing against the main dome to provide
additional stability. The entire system was designed to work together, and
visitors to
Florence can walk between the two domes to see how the
structure connects. The design balances tensile strength and
flexibility, allowing for movement while maintaining structural integrity.
Some
accounts describe additional features that Brunelleschi included, such as small
holes drilled in certain areas to allow for expansion and contraction. A book
called Brunelleschi’s Dome details some of these techniques, showing how
he accounted for forces acting on the structure. His approach combined
practical construction knowledge with an understanding of how materials
interact over time.
Brunelleschi’s
background extended beyond architecture. He was originally trained as a
sculptor and had a broad education, including knowledge of biblical texts. His
ability to connect different disciplines reflects the Renaissance ideal
of a well-rounded individual. Baldassare Castiglione’s book The Book
of the Courtier describes the qualities expected of a courtier,
including skill in rhetoric, mathematics, art, history, and even physical
activities like tennis and weaponry. Brunelleschi shared some of these
qualities, as he combined artistic skill with practical engineering.
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He
also applied what would later be called scientific observation. At the time,
the idea of systematic experimentation and testing was not as formally
established, and the scientific method had not yet been defined.
However, Brunelleschi observed architectural principles from ancient buildings,
such as the Pantheon, and adapted them for new projects. His approach
involved studying past structures, analyzing their construction methods, and
applying those ideas to contemporary architecture.
