The museum was established during Soane's lifetime by a private Act of Parliament in 1833, which took effect on Soane's death in 1837. The Act stated that his house had to be preserved “as nearly as possible” as it was at the time of his death and this remains the case to this day. At the end of the 19th century, the rear rooms of No 12 were connected to the museum in No. 13. Since 1969, No 12 has been governed by the Trustees as part of the museum, home to the research library, offices and the Soane Gallery for temporary exhibitions.

The most legendary spaces found at the rear of the museum. These include top- lit miniatures of the creative lighting manufactured by Soane and used at the Bank of England. The ingeniously calculated Picture Gallery has walls made up of large folding panels, which allow the museum to house three times as many items as the space could normally hold. When visiting, it is necessary to ask to see the panels.

In the museum, you will find around half a dozen rooms in Nos.12 and 13, many of them highly bizarre, but often in delicate ways. The domed ceiling of the Breakfast Room is decorated with convex mirrors; this design has influenced architects from around the world. The library mirrors are influenced by gothic design and the room is decorated in a rich strong 'Pompeian' red. The Study encloses a collection of Roman architectural fragments and the two outer courtyards, the Monument Court and Monk's Yard contain a show of architectural fragments; classical fragments are housed in the Monument Court with its inner column or pasticcio representing architecture. Gothic fragments are housed in the Monk's Yard, which is packed with medieval stonework from the Palace of Westminster.

The Soane's Museum collections include approximately 30,000 architectural drawings, which came from a book of illustrations of Elizabethan houses by John Thorpe to the biggest collection of Robert Adam’s unique drawings. There are also famous architectural models including 15 of Giovanni Battista Piranesi’s original sketches of the Paestum, which hang in the Picture Room. The collection of Neo-classical sculpture includes both plaster and terracotta works by John Flaxman. All these art pieces, from Egyptian art to Italian and Northern Renaissance bronzes, figures and plaques, were collected by Soane himself.

From the painting collection, the best known and most famous are the paintings by William Hogarth, the eight canvases of 'Rake’s Progress' and the four of his well-known political satire “of an Election” created during the Oxford Parliamentary Election of 1754. There are also three major works by the artist Canaletto. The alabaster sarcophagus of Seti I lies in the basement of the museum in what Soane described as the 'Sepulchral Chamber'. Soane held a three-day party in celebration of the piece being added to the collection. The Soane’s Museum is attempting to extend its audience to include the younger generation and to this end, it holds a candlelit opening every first Tuesday of the month from 6 pm to 9 pm., Art shows, talks and tours are available. The museum is quite large but it is possible to see all of the exhibits and the exact way Sir John Soane lived all in one day. Groups of six must book in advance to gain entry together.