The Monument is not merely a memorial. Hooke and Christopher Wren designed it as a functioning scientific instrument, the world's tallest zenith telescope. A central shaft runs from the underground laboratory, accessible through a hatch in the floor of what is now the ticket booth, all the way to a hinged lid in the gilded urn at the top. The plan was to observe stellar transits through this 202-foot tube, and to use the column for gravity and pendulum experiments. Even the 311 steps spiralling to the viewing platform were built to a uniform six-inch height so they could serve as a barometric pressure gauge. It was an audacious marriage of civic pride and empirical ambition. Unfortunately, the rumbling of heavy traffic on nearby Fish Street Hill rendered the experimental conditions hopeless, and the scientific programme was abandoned. The column, however, endured.

Three sides of the Monument's base carry Latin inscriptions describing the fire and the city's reconstruction. The west face displays an allegorical relief sculpture by Caius Gabriel Cibber, showing London as a languishing woman supported by Time, with Charles II directing the rebuilding surrounded by personifications of Architecture, Justice, and Fortitude. But the most revealing text was added in 1681, during the hysteria of the Popish Plot: words falsely blaming Roman Catholics for starting the fire. Alexander Pope, himself Catholic, responded with characteristic venom in verse. The anti-Catholic inscription survived for 149 years before being chiselled away with Catholic Emancipation in 1830. The scars of its removal are part of the monument's story too, evidence that even stone carries the marks of political expedience.

Hooke's surviving drawings reveal several rejected designs for the column: a plain obelisk, a column wreathed in carved flames, and the fluted Doric shaft that was eventually chosen. The real argument was about what should sit on top. Wren initially wanted a phoenix rising from the ashes, but later changed his mind to a statue of Charles II or a sword-wielding female representing triumphant London. The king himself vetoed his own likeness and suggested a simple copper ball with flames sprouting from the top. In the end, it was Hooke's design of a flaming gilt-bronze urn that won out, at a fraction of the cost. The total bill came to 13,450 pounds, eleven shillings, and ninepence, paid mostly to the mason Joshua Marshall. Six years to build, two more to agree on the inscription, and it was done.

The 311-step spiral staircase is narrow and relentless, and for the first century and a half it deposited climbers at an open platform with no barrier between them and the street below. Between 1788 and 1842, six people jumped to their deaths. A mesh cage was added in the mid-19th century, giving the viewing platform the feel of a birdcage perched atop a Doric column. In 1913, suffragettes Gertrude Metcalfe-Shaw and a companion climbed the Monument, unfurled a flag, and rained leaflets on the startled pedestrians of Fish Street Hill. After an eighteen-month closure for refurbishment beginning in 2007, the Monument reopened with a 360-degree panoramic camera on top, updating every minute. The view from the cage remains one of London's most intimate, looking straight down into the narrow lanes where the fire once spread from bakery to church to rooftop, consuming the medieval city that this column was built to remember.