What's the must-see thing in Segovia?

The Aqueduct, without question. Stand in Plaza del Azoguejo at 8am on a weekday and look up. The structure rises 28.5 metres above the cobblestones, 167 arches of pale granite stacked without mortar since approximately the year 200. The stone feels warm to the touch by mid-morning, weathered tawny across 18 centuries of Castilian sun and frost. Pigeons nest between the upper arches while traffic passes through the lower ones. It is the kind of Roman engineering that makes you think about 20,400 blocks overhead, held in place by nothing but gravity and geometry. No ticket, no queue, no reservation. The Aqueduct carried water to Segovia until 1973, and that plain, functional persistence is what separates it from every ruin behind a velvet rope.

From the Aqueduct, walk west along Calle Real through the walled city. The route runs about 1.2 km along a narrow granite ridge between the Eresma and Clamores rivers. You pass through Plaza Mayor, hear the Cathedral bells if the timing is right, and then the ridge narrows to a rocky point where the Alcázar stands above the river confluence. The castle dates to around 1200. It burned in 1862, and most of what you see is a reconstruction completed by the 1890s. That said, the rebuilding was faithful to the original Mudéjar and Gothic forms. The Torre de Juan II has narrow spiral stairs that echo under your feet, the walls close enough to brush your shoulders. From the top, the view runs north across the Eresma valley to the Sierra de Guadarrama. General admission is €9, the tower an additional €3. Worth the extra €3 if your knees allow it.

Segovia Cathedral, started in 1525 on Plaza Mayor, was the last major Gothic cathedral built in Spain. The interior stays cool even in June, a solid 8 or 9 degrees below the 24°C street temperature, and your footsteps on the limestone floor echo in a way that makes you lower your voice. The cloister was moved stone by stone from the earlier cathedral that stood near the Alcázar. Admission is about €3. To be fair, if you are choosing between the three, the Cathedral is the one you could skip without real regret. The 16th-century stonework is clean, the proportions severe. But the Aqueduct and the Alcázar are the two that stay with you after Segovia. The Cathedral is best experienced as a pause on the 1.2 km walk between them, not as a destination on its own.

Segovia sits 90 km northwest of Madrid and works well as a day trip. The bus from Madrid's Moncloa interchange runs roughly every 30 minutes, takes about 75 minutes, costs around €8 each way, and drops you at the Aqueduct in Plaza del Azoguejo. The AVE high-speed train from Madrid-Chamartín reaches Segovia-Guiomar station in 27 minutes, but that station sits about 5 km outside the old city, and you need a connecting bus for the last stretch. For a first visit, the Moncloa bus is the better option. If you stay for dinner, order the cochinillo asado at Mesón de Cándido beside the Aqueduct, where they have served it since 1884. The waiter carves the roast suckling pig with the edge of a ceramic plate to show the skin snaps and the meat yields without a knife, then smashes the plate on the tiled floor. Half a pig feeds two and currently runs about €25-28 per person.