Start around 8:30–9:00 on Île de la Cité, when the island is still relatively calm. Visit Notre-Dame de Paris first, allowing roughly two hours for the cathedral, the surrounding medieval lanes, and security or entry procedures. Entry to the cathedral is generally free, but timed reservations may be released through the official system; arrive with only a small bag, as security queues can be slow. From there, walk a few minutes along the island to Sainte-Chapelle for an intimate hour beneath its extraordinary stained glass. It usually opens around 9:00, with hours varying by season, and timed tickets—roughly €13–15—are well worth arranging ahead. Keep your morning flexible: the two sights are close together, but queues and security can easily add 30 minutes.
Walk or take Métro line 4 from Cité toward Saint-Germain-des-Prés, then settle into Bouillon Saint-Germain for a lively, unfussy French lunch. Allow about an hour and expect approximately €20–35 per person; classic dishes such as onion soup, steak-frites, or a simple egg-mayonnaise suit the old-fashioned bouillon atmosphere. After lunch, head toward the Musée du Louvre by Métro line 4 from Saint-Germain-des-Prés to Châtelet, changing for line 1 to Palais Royal–Musée du Louvre, or simply walk for around 25 minutes if the weather is good.
Reserve a focused two-and-a-half to three-hour visit to the Musée du Louvre, rather than trying to cover every wing. A timed ticket—typically around €22 for non-EU visitors, subject to current pricing—will save considerable time; choose a small route in advance and expect crowds around the Mona Lisa. Exit toward the Jardin des Tuileries and spend your final hour strolling its broad gravel paths, ponds, sculptures, and shaded chairs toward Place de la Concorde. The gardens are free and generally open from early morning until evening, with seasonal closing times, making them an easy, unhurried finish after the museum.
Begin around 9:30 in Montmartre at the Musée de Montmartre, a calm introduction to the neighborhood’s cabarets, studios, and artistic past. Allow about 1½ hours; the museum typically opens at 10:00, with admission around €15–€18. From Jardins Renoir, walk uphill through the quieter lanes toward Basilique du Sacré-Cœur de Montmartre—roughly 15 minutes, with steps and cobbles—then visit the basilica and take in the panoramic view from the forecourt. Entry to the basilica is free; the dome has a separate fee of roughly €8–€10 and involves many stairs, so skip it if the view from the hill is enough.
Walk down toward Place du Tertre and have lunch at Le Relais Gascon, known for generous southwestern-style salads and plates; expect about €20–€35 per person, and go before 12:30 or after 14:00 to avoid the busiest period. Afterward, take Métro line 4 from Barbès–Rochechouart to Gare de l’Est, then change to line 5 for Jacques Bonsergent or République—about 25–30 minutes total—and stroll along Canal Saint-Martin for around 1½ hours. The tree-lined towpaths and iron footbridges are especially pleasant in the afternoon; bring water, since the canal itself has few places to pause for shade.
Continue by Métro line 5 from République to Bastille, then walk about 10 minutes into Le Marais for Marché des Enfants Rouges. The market usually closes in the late afternoon or early evening, with schedules varying by day, so aim to arrive by 16:30; allow 1–1½ hours and budget €15–€30 for grazing between stalls. Finish with a relaxed walk to Place des Vosges, about 10 minutes away, where you can sit under the arcades or on the lawns before dinner. It is a good place to end without adding another formal visit—wander the surrounding streets of Le Marais as the light softens, then use Métro line 1 from Saint-Paul or Bastille for the journey back.