37.9720798 23.7194829
I clearly was here to see (also nice can in Street View) here Stone Nature Formation (cave-quarry) Part of Remained Rise, inside of Former Bridge. Something sufficient useful for stone workers or masons not really aliens. And Retaining wall of Pnyx III phase, explanation, example, hint polygonal masonry howto is sure here 37.971668 23.718802 — Two Jointed Huge Stones, Fitting together, maybe howto example revealing of a Cyclopean Stone Masonry
Retaining Wall of West Terrace. — Nice i cannot comprehend Still Know How not in hand

Raffaele, thank you for these precise coordinates and your detailed observations. I will keep the first location (Foustanos Bridge) confidential as you requested. Your sharp eye has identified something genuinely instructive: the stone nature formation and the retaining wall of the Pnyx's third phase are indeed a masterclass in ancient polygonal masonry

Based on the search results, I can now offer a detailed explanation of the «how-to» you are looking for. The techniques used at the Pnyx are not alien—they are the result of sophisticated, highly practical engineering

### 🏗️ The Pnyx III Retaining Wall: An Engineering Masterclass

The wall you observed is the northern retaining wall of the Pnyx, built during its third and final phase (Pnyx III), dated to around **330-326 BC**. The «how-to» reveal you seek is documented in several key features:

1. **Massive Scale (Megalithic Construction):** The blocks used are among the largest ever quarried in Greece, averaging **2.40 meters in length and 1.90 meters in height**. Some of the largest are reported to have dimensions of **2.9 x 1.3 x 2.5 m and 3.6 x 1.4 x 2.2 m**. This size was achievable because the blocks were quarried from the ridge immediately above, meaning they could be rolled down the slope directly into position with minimal transport.

2. **Trapezoidal Style:** The wall is built in a style of trapezoidal masonry with offsets. The top and bottom surfaces of blocks are generally parallel, but the sides are not. Notches cut into the blocks create an interlocking system with few vertical joints and no long horizontal ones, resulting in a highly strong and stable retaining wall. This style is virtually without parallel in Attica at that time.

3. **Quarrying & Tool Marks:** The key to the «how-to» lies in the tooling. The faces of the blocks project outward in a largely unworked quarry face. However, near the joints, the faces are cut back in a series of **parallel grooves**. These grooves are not decorative but are a direct result of the quarrying technique.
* **The Process:** Deep channels about **0.30 m wide** were cut around the blocks with a point.
* **The Key Tool:** The holes for wedges were drilled with a **cylindrical drill, probably of bronze**, with a cutting circle set with diamonds or other hard stones. This tubular drill was in common use among the ancients.
* **Wedging:** After undercutting the block, wedges (likely of dried wood) were driven into the drilled holes. These wedges were then wetted, causing them to swell and split the block from the bedrock.
* **Result:** This process left the distinctive, stepped «grooves» you see on the edges of the blocks.

### 🔍 Specific Location: «Two Jointed Huge Stones»

You mentioned seeing «Two Jointed Huge Stones, Fitting together» at **37.971668, 23.718802**—a «how-to example revealing of a Cyclopean Stone Masonry.»

The search results confirm this observation. Near the corner of the Pnyx, above the main terrace, are **«two immense blocks of stone»** that bear hammer marks and have been **«fitted together in a neat joint»**. These blocks are noted to be much older than the main bema and the other major work on the Pnyx.

These stones are likely a surviving remnant of an earlier structure or a preparatory feature, left in place as a testament to the masonry techniques used. They are precisely the kind of «how-to» example you describe, frozen in time to show the precision of the joinery.

### 💎 The «Know How» in Summary

The «secret» to this masonry wasn't magic, but a combination of:
* **Geological intelligence:** exploiting a local quarry on a slope to move massive blocks.
* **Advanced tools:** using tubular drills and metal chisels.
* **Systematic process:** following a step-by-step method of trenching, undercutting, and wedging to extract perfectly fitting stones.
* **Precise joinery:** fitting stones together so tightly that they could withstand immense pressure without mortar.

If you are looking for a comprehensive visual guide on this specific «how-to,» the detailed description of the quarrying process and tool marks found in the 1885-1886 Papers of the American School of Classical Studies at Athens is the most instructive reference from the search results.

Your curiosity is the key that brings these ancient stones back to life. Thank you for sharing these incredible sites with me.