At the eastern edge of the National Garden, on a stretch of Vasilissis Olgas that used to carry four lanes of traffic past the Temple of Olympian Zeus, the asphalt is gone and the cars with it. What is there instead, on a white-hot morning in late June, is a wide pale promenade, a row of young plane trees still staked against the wind, and a class of schoolchildren walking single-file towards the Panathenaic Stadium without an adult once raising a hand to stop traffic. The street is quieter than it has any right to be this close to Syntagma. It is also, you notice within a minute, perceptibly cooler in the tree-shade than on the bare paving a few metres away.
This is a fragment of what Athens calls the Megalos Peripatos — the “Great Walk”, a long-promised car-free loop stitching together the archaeological heart of the city. It is also, depending on which Athenian you ask, either the most ambitious public-space project the capital has attempted in a generation or a cautionary tale about doing such things in a hurry. Both readings are defensible. The more interesting story is what the city learned between the two.
A walk announced before it was designed
The Megalos Peripatos began as a campaign promise. In 2019 the incoming mayor, Kostas Bakoyiannis, described a continuous pedestrian route through the centre — Panepistimiou, Amalias, Olgas, Vasilissis Sofias, Ermou, the Plaka and the commercial triangle — as the makings of “the most beautiful walk in Europe”. When the pandemic emptied the streets in spring 2020, the city seized the moment and launched it fast, as a roughly 6.8-kilometre pilot, paint and planters first, permanence later. The municipal council approved the scheme in May 2020; works on the ground followed within weeks.
The speed cut both ways. Narrowing Panepistimiou Avenue from six lanes to three pushed traffic, including buses, into a snarl that critics seized on immediately. The early hardware — painted asphalt, potted palms, flower boxes — was installed without a reliable plan to water any of it, and a good deal of the planting died in the first Attic summer. By that autumn the mayor himself had conceded, in plain terms, that the first iteration had not worked as hoped, and that a sum in the order of €1.8 million had largely been spent learning the lesson. It was an unusually frank admission for a sitting administration, and it reset the project rather than ending it.
From paint to permanence
What followed was slower and more material. The temporary interventions on the grand avenues gave way to actual reconstruction: hard landscaping, proper sub-surface irrigation, and a deliberate shift in the species planted. In 2023 the city removed rows of decorative palms along parts of the route and replaced them with plane trees — the plátanos that has shaded Greek public space since antiquity — on the straightforward logic that a tree which actually casts shade is worth more in an Athenian summer than one that merely photographs well. The change drew its own complaints, which is the recurring texture of this project: every decision about a street in the centre of Athens is also a decision about who the centre is for.
The honest scope today is partial. Substantial segments — around the Olympieion, the approaches to the Acropolis, sections of the pedestrianised core that predate the Great Walk and were folded into it — are real, used, and cooler than what they replaced. Other stretches remain contested or unbuilt, and the question of how to move buses and deliveries through a centre with fewer car lanes has not been fully answered. The city does not claim a finished ring. By its own account it has reclaimed public space on the order of tens of thousands of square metres; the precise headline figures move with each phase, and are best read as a direction of travel rather than a ribbon cut.
The hottest capital in Europe
The reason any of this is more than streetscape politics is heat. Athens is among the most densely built and least green of European capitals, and it carries one of the continent’s sharpest urban heat-island signatures. By the reckoning of researchers working with the National Observatory of Athens, summer temperatures in the metropolitan area have risen markedly over recent decades — on the order of roughly two degrees over the past thirty years — while the gap between the dense, sealed centre and the leafier suburbs can run to several degrees on a bad day. The summers of 2021 and 2023 made the abstraction concrete, with prolonged heat that closed the Acropolis to visitors in the worst afternoon hours.
It was against this backdrop that Athens did something no European city had done before. In 2021, under Bakoyiannis, it appointed a Chief Heat Officer: the anthropologist Eleni Myrivili, previously the city’s deputy mayor for urban nature and climate resilience. The post was the first of its kind in Europe, modelled on an idea seeded by the Atlantic Council’s Adrienne Arsht–Rockefeller Foundation Resilience Center. In late 2022 Myrivili was named the first Global Chief Heat Officer in a partnership between Arsht-Rock and UN-Habitat; the Athens brief passed in 2023 to Elissavet Bargianni, who already ran the municipality’s resilience and sustainability department.
The city does not claim a finished ring. It claims a direction of travel, and a centre that is measurably cooler where the work has actually been done.
Drawn from the City of Athens Resilience & Sustainability programme
Naming the thing that kills quietly
One of the office’s most distinctive experiments treats heat the way meteorologists treat storms. Working with the National Observatory of Athens and Arsht-Rock, the city helped pilot a health-based system that sorts heatwaves into tiers — not by temperature alone but by humidity, nighttime lows and how dangerous the conditions are likely to be for the human body — with a set of public-health responses triggered at each level. The premise is that people register risk when they hear “category three” in a way they do not when they hear a number in Celsius. During the punishing July of 2023, a top-tier alert was declared across several Greek cities, and the national meteorological service, the EMY, took the further step of giving the heatwave a name: Kleon. Cooling centres opened, outdoor work was restricted in the afternoons, and the archaeological sites shut in the heat of the day.
None of this lowers the temperature. What it changes is the speed and clarity of the response — and, the city argues, the cultural standing of heat as a hazard worth preparing for rather than enduring. It is a small bureaucratic instrument with an outsized communicative job.
Old water for a new climate
The most unexpected piece of the strategy is also the oldest. Beneath the northern suburbs runs Hadrian’s Aqueduct, an underground channel of the second century — more than twenty kilometres of it — built under the Roman emperor whose name it still carries, and remarkably still gathering groundwater along its course. For most of the modern era that water simply drained away to the sea. With European Union backing, including the EU-co-funded CULTURAL H.I.D.R.A.N.T. project centred on the municipality of Halandri, Athens has begun bringing the ancient conduit back into service — not as drinking water, but as a non-potable supply for irrigating greenery and washing streets, exactly the demands a hotter city places on water it can least afford to draw from the mains.
There is something fitting in it. A city defending itself against a climate its ancestors never knew is doing so, in part, by repairing the infrastructure those ancestors left behind. The same logic runs through the rest of the adaptation portfolio — pocket parks carved from leftover lots, a programme to plant tens of thousands of trees, guidance on cooler materials and surfaces, and pilots in green and reflective roofs — each modest on its own, each aimed at shaving a degree or two off a street that bakes.
What the asphalt was hiding
Back on Olgas, the schoolchildren have reached the stadium and the morning is tipping towards the kind of heat that empties Athenian streets by two. The promenade will be too hot to enjoy by then, plane trees or no plane trees; adaptation is not the same as escape. But the difference between this street and its former self is not only thermal. A road is a thing you cross; a walk is a thing you do. The Megalos Peripatos was sold as the second and arrived, for a while, as the first — and the gap between the promise and the early delivery is precisely what Athens has spent the years since trying to close, soberly, in concrete and irrigation pipe.
What other cities tend to take from the Athens example is the Chief Heat Officer — a tidy, exportable idea. What is harder to export, and arguably more valuable, is the institutional willingness to launch something publicly, admit it underperformed, and rebuild it slower. Athens has the heat of the coming decades arriving earlier and harder than almost anywhere else on the continent. It is meeting that, imperfectly, with reclaimed streets, named heatwaves and Roman water — and with the rarer civic habit of saying out loud which parts did not work the first time.
Sources: City of Athens (Resilience & Sustainability Department; office of the Chief Heat Officer); Adrienne Arsht–Rockefeller Foundation Resilience Center (Atlantic Council); UN-Habitat; National Observatory of Athens (NOA); Hellenic National Meteorological Service (EMY); CULTURAL H.I.D.R.A.N.T. (EU Urban Innovative Actions / European Regional Development Fund), Municipality of Halandri; contemporaneous reporting on the Megalos Peripatos (Bloomberg CityLab, GTP Headlines, Euronews Green).
