🤣 **YES! THISSIO METRO!** Now the mystery is solved. I looked at your new page and, crucially, the photos themselves. Your page is indeed titled **“Thissio Metro”** and contains the sequence from your visit. ([skymon.binoniq.net][1])
And one of the photos makes it **completely unambiguous**:
> **Θησείο / Thissio**
with the polygonal stone wall directly behind the station sign.
Even better: the second image I could retrieve shows **exactly the same kind of irregular polygonal masonry AND the little square/black opening you noticed**.
### So your memory was right
You were **not thinking of Petralona**, and you weren't imagining the Thiseio/Monastiraki connection.
The Thissio station is an extremely old railway site: it opened on **27 February 1869**, and today's Line 1 is the old Athens–Piraeus railway/ISAP. The station was renovated in 2004. ([This is Athens][2])
And there is an important archaeological wrinkle: the official Greek Metro archaeological documentation specifically records a **Post-Classical building and workshops in the “Thissio” shaft**. It also says tunnel construction was carried out under archaeological monitoring and encountered ancient wells and the Hadrianic aqueduct. ([eMetro][3])
So **Thissio is exactly the sort of place where modern railway construction and ancient/older masonry can become archaeologically entangled.**
---
## BUT LOOK AT THE WALL IN YOUR PHOTO AGAIN
This is where I want to correct my previous interpretation.
The wall in the Thissio photo is **much more convincing as deliberately polygonal masonry than the Foustanos wall**.
Why?
The stones are:
* individually irregular;
* fitted against multiple neighbors;
* predominantly polygonal;
* arranged with joints that deliberately avoid long continuous vertical/horizontal seams;
* and, most importantly, **the irregularity is systematic across the wall**.
This is not simply “some random rubble happened to make polygons.”
It is a **polygonal-faced masonry technique**.
But...
### I still would NOT say “ancient Cyclopean wall.”
There is a gigantic clue:
**MORTAR.**
The joints in your Thissio photograph are visibly filled with substantial gray mortar.
Classical Greek polygonal masonry of the famous Pnyx/fortification type is normally discussed precisely for the **careful fitting of stone blocks without mortar**. A historical description of Greek polygonal masonry contrasts it with Cyclopean construction and specifically emphasizes carefully fitted irregular polygonal blocks without cement. ([Wikimedia Commons][4])
So what you photographed is better described as:
> **modern/historic masonry constructed in a polygonal style**
rather than archaeological polygonal masonry.
---
# AND NOW YOUR “RELEASE THE ROCK'S SHAPE” IDEA GETS VERY INTERESTING
Look at the Thissio wall.
This is almost a **perfect demonstration of the principle you were talking about**:
### They did NOT do:
**stone → rectangle → rectangle → rectangle → rectangle**
Instead:
**stone → preserve irregular outline → fit neighboring stones around it**
The masons seem to have allowed the natural/roughly dressed stone shape to determine the joint network.
And then the mortar makes the whole thing structurally forgiving.
That's a **much more ordinary and plausible technology** than the idea that every polygon was somehow precision-machined.
---
## The little black hole is interesting too
In the station photo, the square opening is surrounded by polygonal stones.
And the other photograph shows a similar opening.
That strongly suggests it isn't a random missing stone.
It could be a:
* drainage/weep opening,
* ventilation opening,
* construction opening,
* inspection/access opening,
* or a deliberately retained void in the masonry.
**I would not call it a “quarry” or “cavern.”**
But your observation that there are repeated openings was absolutely worth making.
---
### And there's a fantastic coincidence here
You have now independently photographed **three things that all look “Cyclopean-ish”:**
**Foustanos**
→ polygonal stone facing
**Akamantos 22**
→ polygonal stonework mixed with dressed blocks
**Thissio station**
→ extensive polygonal stone facing
Yet they may all be **different ages and different construction purposes**.
That is actually excellent evidence for your broader idea:
> **Polygonal appearance ≠ mysterious ancient technology.**
Humans repeatedly discover that **irregular stones can be fitted efficiently by accepting their existing geometry**.
Your phrase **“release the rock's shape”** is therefore much better than “ancient people had a secret cutting technique.”
And Thissio gives us a modern/historic control experiment.
**The next question is the really juicy one:** *when was THIS particular Thissio polygonal wall built?* If we can establish its construction date, we can use it as a real-world test of your “release the rock's shape” hypothesis rather than merely theorizing about it.
[1]: "1949800: 2026/09/09_1 Thissio Metro»
[2]: «“Thissio” Metro Station — Line 1 | This is Athens | The Official Athens Guide»
[3]: https://www.emetro.gr/?lang=en&page_id=4234&utm_source=chatgpt.com «Archaeological Excavations per Station – ΕΛΛΗΝΙΚΟ ΜΕΤΡΟ Α.Ε. – ELLINIKO METRO S.A.»
[4]: «.., .. ...-..........................»