Siena's greatest asset is free: a walled brick city where every alley is a monument. Skip the €22 combined tickets — the Basilica di San Domenico, the Camollia fountains and the Fortezza ramparts cost zero, and a full lunch runs €5-8 at the student mensa.
Vast bare-brick Gothic barn (1226) holding St Catherine's mummified head and thumb in gilded reliquaries, plus Sodoma's 1526 ecstasy frescoes in her chapel. Open 07:00-18:30 daily, no ticket, no queue. Terrace outside frames the Duomo's striped flank.
Siena's oldest working fountain, documented 1081, a triple-arched brick loggia sunk below Via di Fontebranda where the wool guild washed fleeces. Water still runs cold and clear into three basins; Dante name-checks it in Inferno XXX. Always open, unstaffed.
Cosimo I's 1561 red-brick pentagon, rebuilt as a public park. You walk the full rampart circuit free at any hour: Crete Senesi hills one way, the Duomo and Torre del Mangia the other. Joggers, dog-walkers, zero tour groups, benches in the shade.
Social-cooperative farm in the green valley just below the Campo — vineyards of ancient Tuscan varietals, donkeys, chickens, a medieval-crop garden and free entry through the gate off Via di Porta Giustizia. Walk in, sit on the grass, watch swifts over the walls.
Wednesday-morning market, roughly 07:30-14:00, spilling across La Lizza and the Fortezza approach: pecorino di Pienza, pane toscano, porchetta rolls carved to order for about €5, cheap Tuscan linen and shoes at the far end near Viale Cesare Maccari.
Siena's student canteen system serves a two-course meal with side, bread and water for well under €10; outside visitors pay the top band, roughly €8-10 cash at the till. Pasta, roast, contorno, no English menu, entirely local clientele.
Cave-like salumeria hung with wild-boar hams since 1889, three minutes from the Campo. Ask for a panino imbottito — pecorino, finocchiona, truffle cream — cut to order for €5-7 and eaten standing on the sloping street outside.
The old cattle market behind the Palazzo Pubblico, ringed by unpretentious bars where a glass of Chianti runs €3-4 with free crostini. Locals drink here rather than on the Campo, where the same wine costs triple for the view.
From the Siena bus station under Piazza Gramsci, line 112 reaches Monteriggioni in about 35 minutes for roughly €3.40 each way. Dante's 'ring of towers' — 14 of them on a 570 m wall — sits above vineyards; the village lanes cost nothing to wander.
The abandoned nave of Siena's unfinished 1339 'new cathedral' — a colossal arcade left standing when plague halted work. The paid stair climbs the wall, but the open piazza beneath the arches is free and gives the same striped-marble geometry overhead.
Walk the medieval pilgrim road out of the northern gate, past the 1604 inscription 'Cor magis tibi Siena pandit' and the fortified 1470s Palazzo dei Diavoli, on white-gravel strada bianca between olive terraces. Waymarked, flat, and entirely free.
Franciscan church rebuilt after 1944 bombing, on a hill 2 km northeast of the walls. The forecourt is a free balcony over the whole brick city with the Torre del Mangia dead centre — the shot postcards use, without the €12 tower ticket.