The Etruscan and Roman foundations underneath the lagoon town
Orbetello's spit-of-land setting is older than its walls. The Etruscans of Vulci and Tarquinia worked this stretch of the Tuscan coast from the 7th century BCE — the polygonal Etruscan wall section still visible at the eastern end of the modern town defenses pre-dates everything Roman or Spanish around it. Rome absorbed the area in the 3rd century BCE and founded the colony of Cosa in 273 BCE on the Ansedonia promontory just south of the lagoon, partly to garrison the conquered Etruscan coast. Cosa's forum, capitolium, and city walls are among the best-preserved Republican-era Roman colony remains in central Italy and have been excavated by the American Academy in Rome since the 1940s. The lagoon itself is Etruscan-era: salt was harvested here under the Etruscans, the Romans, the medieval Aldobrandeschi counts, and the Spanish in turn — the same body of flat water the kite school launches on has been a working economic surface for roughly 2,500 years.
Stato dei Presidi — the Spanish coastal kingdom that built the old town
Most visitors clock the fortifications as 'Italian' or 'medieval'; they are neither. From 1557 to 1707, Orbetello was the capital of the Stato dei Presidi — a Spanish coastal protectorate carved out by Philip II to control the Tyrrhenian shipping lanes between Naples and Genoa. The pentagonal bastioned walls of Orbetello, the fortifications of Porto Ercole (Forte Stella, Forte Filippo) and Porto Santo Stefano, and the polveriera (powder magazine) on the lagoon front are all Spanish military architecture of the late 16th and 17th centuries — built to a Habsburg trace italienne design rather than to local Tuscan precedent. Spanish administration ended with the War of Spanish Succession in 1707; the territory passed to Austria, then to the Bourbons of Naples, and finally to the Kingdom of Italy at unification in 1861. The Caravaggio connection: the painter died at Porto Ercole in 1610 while on his way back from exile, almost certainly inside the Spanish presidio.
Italo Balbo and the 1933 transatlantic flying boats — Orbetello as Atlantic launchpad
From 1925 to 1937, the Orbetello lagoon was the Italian Air Force's principal seaplane base under Italo Balbo, fascist Italy's air minister and the era's most internationally famous aviator. The lagoon's flat, sheltered water was uniquely suited to launching heavy flying boats. Balbo led two mass-formation transatlantic crossings from Orbetello: the South Atlantic Crociera in 1930–31 (Orbetello to Rio de Janeiro, 12 Savoia-Marchetti S.55s) and the more celebrated Crociera Aerea del Decennale in 1933 (Orbetello to Chicago and back, 25 aircraft, lionized at the Chicago World's Fair, where 'Balbo Drive' is still named for him). The hangars and the Idroscalo control tower on the eastern edge of the lagoon are surviving Fascist-era aviation architecture. Honest framing: this is a complicated heritage. Balbo was a senior figure in Mussolini's regime; the flights were a propaganda showcase for fascist Italy as well as a genuine engineering achievement. The buildings stand; how to read them is up to the visitor.
Maremma — from malarial reclamation to Italy's quietest coast
Until the mid-20th century, the Maremma — the coastal Tuscan plain Orbetello sits in — was synonymous in Italian usage with malarial swamp, banditry, and rural poverty. The Etruscan-era lagoons and the Roman drainage works had silted up over the medieval centuries; by the 19th century the lowlands between Grosseto and the sea were largely depopulated, worked seasonally by butteri (Maremmana cowboys) who ran long-horned Maremmana cattle and wild horses across the marshes. Comprehensive bonifica (land reclamation) began under the Lorraine grand dukes of Tuscany in the 1820s, accelerated in the early 20th century, and was largely completed under Mussolini's regime in the 1930s — draining canals, planting the umbrella-pine windbreaks that now line Feniglia and Giannella, and finally eliminating endemic malaria after WWII with DDT spraying campaigns. The result is the Maremma you see today: agricultural plain, pine forests on the tomboli, the WWF and Uccellina reserves protecting what was deliberately not drained, and a rural quietness that still distinguishes this coast from the rest of Tuscany. The Morellino di Scansano wine zone — DOCG since 2007 — is itself a post-reclamation phenomenon, planted on land that wasn't farmable until the 20th century.