Europe's most private-feeling museums – collectors' houses in London, Paris, Milan, Rome and Cap Ferrat

Europe's great house museums have something the national galleries cannot offer: the sense of being a guest. The pictures hang where a collector chose to hang them, the furniture is the furniture they sat on, and the rooms are sized for a household rather than a crowd. Most exist because someone – often a widow, sometimes a disappointed father – decided that a collection should outlive the family and left house and contents to the nation or an institution. The terms of those bequests are why the rooms still look the way they do.

The Wallace Collection, London

Hertford House on Manchester Square was the London townhouse of the Marquesses of Hertford. The collection was built chiefly by the 4th Marquess, who left it and the house to his illegitimate son, Sir Richard Wallace; Wallace's widow bequeathed the lot to the nation, and it opened to the public in 1900. Its 25 galleries are strongest in French eighteenth-century painting, furniture and porcelain – Fragonard, Boucher, Watteau – with Old Masters including Titian, Rembrandt, Hals and Velázquez, and one of the great collections of arms and armour. Entry is free.

Sir John Soane's Museum, London

The architect John Soane secured a private act of Parliament in 1833 that took effect on his death in 1837: his house next to Lincoln's Inn Fields and its contents would pass to trustees for the nation and be kept, as nearly as possible, exactly as he left them. He did it in part to disinherit a son he disliked. The result is one of the most extraordinary interiors in London, crowded with antiquities, architectural models and paintings, including Hogarth's eight canvases of A Rake's Progress and four Canalettos. Only 90 visitors are allowed in at a time. It is free, with no pre-booking required.

Musée Jacquemart-André, Paris

On the Boulevard Haussmann stands the mansion the banker Édouard André built between 1869 and 1875. He married the society painter Nélie Jacquemart, and every year the couple travelled in Italy, assembling one of the finest collections of Italian art in France. After his death she completed their "Italian Museum" and, as they had agreed, bequeathed house and collection to the Institut de France. It opened in 1913. The Florentine rooms hold Botticelli, Perugino and Uccello's St George and the Dragon; the Venetian rooms Mantegna, Bellini and Carpaccio.

Musée Nissim de Camondo, Paris – for later

On the edge of Parc Monceau, Count Moïse de Camondo built a house between 1911 and 1914, modelled on the Petit Trianon, for his collection of eighteenth-century French decorative art. He left it to Les Arts Décoratifs in memory of his son Nissim, killed in the First World War. It is one of the most moving house museums anywhere – and it is currently closed for renovation, with reopening announced for the beginning of 2030.

Museo Poldi Pezzoli and Museo Bagatti Valsecchi, Milan

Milan has two, a few minutes apart. The Poldi Pezzoli, on Via Manzoni near La Scala, was the home of Gian Giacomo Poldi Pezzoli, who had rooms redecorated to match the paintings hung in them; he left it to the Brera Academy, and it opened on 25 April 1881. Badly damaged in the Second World War, it reopened in 1951; the art had been stored safely. Its strengths are northern Italian and Netherlandish painting.

The Bagatti Valsecchi, in the fashion district around Via Montenapoleone, was assembled by the Barons Bagatti Valsecchi and displayed in their home as they wished: Renaissance furniture, maiolica, tapestries, arms and armour, and paintings including works by Giovanni and Gentile Bellini. After a morning there, our guide to Milan's restaurants covers lunch.

Galleria Borghese, Rome

The Borghese is the grandest house on this list and still a villa at heart: a villa suburbana built for Cardinal Scipione Borghese, nephew of Pope Paul V, by Flaminio Ponzio from the cardinal's own sketches. Scipione was an early patron of Bernini and an avid collector of Caravaggio, and the rooms are filled accordingly – Caravaggio's Boy with a Basket of Fruit and Sick Bacchus, Titian's Sacred and Profane Love, Raphael's Entombment, and Bernini's sculpture. Check the museum's booking rules before you go.

Villa Ephrussi de Rothschild, Saint-Jean-Cap-Ferrat

The Riviera's entry is a pink villa on the isthmus of Cap Ferrat, built between 1907 and 1912 for Baroness Béatrice de Rothschild to designs by Aaron Messiah. She filled it with antique furniture, Old Master paintings and rare porcelain, and laid out nine themed gardens – French, Spanish, Japanese, Florentine, Provençal and more – now listed among the Remarkable Gardens of France. On her death in 1934 she left it to the Académie des Beaux-Arts. For the rest of the coast, see verapi.fr.

How to visit

These are small places, and they reward going early or late in the day. Allow time: the point is to linger in a room, not to tick off a masterpiece. Opening days and booking rules vary and change, so check each museum's own site before travelling. More exhibitions and openings in our culture section and on metromode.co.

For a weekend. For a lifetime.