Carcassonne rewards the tight budget: the lices between the double walls, the basilica, the fine-arts museum and every viewpoint over the Cité cost nothing. Add a Place Carnot market picnic and a €1.10 bus to the lake and three days run under €60.
The grassy corridor between the two ring walls is open day and night with no ticket — 3km of ramparts and 52 towers seen from below. Enter at the Porte Narbonnaise before 09:30 and you share the lices with joggers, not coach groups.
Free entry to the Cité's 11th-century church, whose Gothic transept holds the finest 13th- and 14th-century stained glass in southern France. Open roughly 09:00–11:45 and 13:45–17:00; the rose windows burn brightest near midday.
The city's fine-arts museum on Rue de Verdun charges nothing: Flemish 17th-century canvases, French still lifes and a full room of local painter Jacques Gamelin. Open Tuesday to Saturday, mornings and afternoons, closed Sunday and Monday.
The 14th-century pedestrian bridge between the bastide and the Cité gives the postcard angle on the fortress for free. Cross from the lower-town side and stop mid-span; the floodlights come on at dusk, around 21:30 in midsummer.
Tuesday, Thursday and Saturday mornings the bastide's arcaded square fills with Aude producers: goat cheese, Lucques olives, apricots, saucisson sec. Bread, cheese, sausage and fruit for two comes to roughly €10 total.
The largest public garden in the lower town sits between the market and the river: cedar shade, benches, a fountain basin and a clear sightline to the Cité on its hill. Free public toilets stand at the northern corner.
The garden bar hidden behind Saint-Nazaire in old cloister ruins pours Corbières and Minervois by the glass from about €3.50, with a charcuterie plate near €9 — the cheapest sit-down table inside the walled Cité.
The canal basin at the bastide's northern edge costs nothing to walk: plane-tree towpath, hire boats mooring for the night, and the fortress on the skyline behind them. Ten minutes on foot from the train station.
The municipal lake 5km east of town has free swimming beaches, lifeguards through July and August, and a 6km loop path through garrigue and pine. City Agglo'Bus tickets cost €1.10 one way from the bastide.
A walled terrace garden laid out in the 1820s on the Cité's southern slope, planted with cypresses and stations of the cross. Entry is free, the gate is easy to miss, and the benches look straight down the Aude valley.
The bastide's 14th-century Gothic church has the widest nave in Languedoc after Toulouse and is free to enter; the guided climb up the 54m tower runs in summer for around €4 and delivers the full Cité panorama.
The hill south of the Aude, reached by the Chemin des Anglais, is the free wide-angle sunset position: the whole double wall in profile with vineyards in the foreground. About 35 minutes uphill from the Pont Vieux.