The striped arches
Granite and brick alternating in visible courses.
doalex — CC BY-SA 3.0 · Lorenzo Vallés — CC BY-SA 3.0 · Lorenzo Vallés — CC BY-SA 3.0 · Falk2 — CC BY-SA 4.0
**A file of striped stone-and-brick arches standing in an open field — the name given by locals in astonishment that it survived** — northwest of Mérida. Built in the **1st century AD** to bring water from the artificial lake of **Proserpina** into the city, **a distance of some five kilometres**. ⚠ **About eight hundred metres and thirty piers survive**, **some twenty-five metres high**. ✅ **Its construction is striped**: **alternating courses of granite and brick** — ⚠ **not ornament but technique**: **brick is lighter and quicker in the upper parts**, **granite stronger at the base**. ⚠ **The name is popular**: **locals called it «the miracles»** because its survival seemed to be one. ✅ **It stands today in an open free park**, **and storks nest on it.**
Granite and brick alternating in visible courses.
Birds nesting on the pier tops in spring.
Standing among the piers gives the true scale.
Avenida Via de la Plata, 06800 Merida, Spain
The Temple of Diana**A Roman temple standing with its columns in the middle of a modern street — wi12 minutes walk4.8
National Museum of Roman Art**A red-brick building of immense arches designed by Rafael Moneo — reckoned amo13 minutes walk4.8
The Alcazaba of Mérida**The oldest Islamic fortress in Spain — built in 835 from reused Roman stone** 14 minutes walk4.4
The Roman Amphitheatre**An amphitheatre for fifteen thousand, directly adjoining the theatre — with it16 minutes walk4.7
The Roman Theatre of Mérida**The best-preserved Roman theatre in Spain — its stage front still standing in 16 minutes walk4.7**By a constant and extremely precise gradient — the channel falls a few centimetres per kilometre.** ✅ **The principle**: **water runs by gravity** — ⚠ **so every metre of the route must be slightly lower than the one before**, **from source to city**, **without a single exception**. ✅ **And the gradient must be exact**: ⚠ **too steep → the water accelerates, erodes the channel and overflows at bends**; ⚠ **too shallow → it stagnates, silt settles and the channel blocks**. ✅ **So the Romans used gradients of **a few centimetres per kilometre** over long sections** — **an astonishing precision across tens of kilometres**. ✅ **The instruments**: the ***chorobates*** — a timber frame with a water level for measuring horizontality — **and the *groma*** for alignment; ⚠ **simple tools used thousands of times with patience**. ✅ **And most of an aqueduct runs underground**: ⚠ **arcades are the exception, not the rule** — **built only to cross a valley or a dip**, **because they are expensive**; **and what you see here is the part that could not be avoided**. ✅ **Where a valley was very deep** they used an **inverted siphon** — pressure pipes running down and up.