Monty Python and an £8m extension for the museum of shrunken heads

Shrunken heads, totem poles, exotic costumes and a bottle that allegedly has a witch trapped inside – a good place to look for these and other curiosities is the Pitt Rivers Museum at Oxford University, which opened an £8m extension yesterday.

Michael Palin, the television explorer who has been the museum's patron and fundraiser since the 1990s, joined the university's vice-chancellor, Dr John Hood, for the opening ceremony. "I have always loved Pitt Rivers' wonderful eclectic displays," Palin said. "In an over-regimented world, they engage and stimulate the curious, and encourage a genuine spirit of discovery."

The former Monty Python star put up the money to pay a year's wages for a technician, Chris Wilkinson, to pack and unpack the museum's exhibits, which had to be moved while work on the extension was in progress. Mr Wilkinson was known throughout the year as "the Palin technician". Indeed the curator, Laura Peers, is reputed to have been so grateful for the funding that she offered to imprint the words "Palin technician" on Mr Wilkinson's forehead with tools from the museum's collection, but he modestly turned down the offer.

The museum, which attracts nearly 200,000 visitors a year, was founded in 1864 when General Augustus Pitt Rivers, an amateur archaeologist and anthropologist, donated his collection of 18,000 objects to Oxford University on the condition that a permanent lecturer in anthropology was appointed. Museum staff teach at the university even today and the collection has grown to about 500,000 items, many of them donated by travellers, scholars and missionaries.

The museum is famous for its exotic exhibits, including shrunken heads from the Amazon forest of Ecuador, where the ferocious Jivaro, or Shaur, warriors used to decapitate enemies and treat the heads with hot stones and sands.

Another famous object has a handwritten label identifying it as a "silvered and stoppered bottle said to contain a witch. Obtained about 1915 from an old lady living near Hove, Sussex. She remarked: 'And they do say there be witchs in it and, if you let un out, there'll be a peck o' trouble'." Another, from the Solomon Islands, is simply marked as "charm used to cause death of enemy". A third is labelled: "Night-horse. By mounting this, a member of the Mba tsav secret society gains invisibility and can travel far at night, kill an enemy, and return."

The museum owns a set of 54 Noh masks used in classical Japanese drama, which were bought from a Tokyo theatre in the 1870s. A Tahitian mourner's costume collected during Captain Cook's second voyage, in 1773-4 is also on display, along with masks from Africa, Melanesia and North America.

The new building has a conservation laboratory, library, facilities for visiting researchers, another exhibition gallery and a lecture theatre. The next phase of its expansion will clear the museum's cluttered entrance hall, which has been full of glass exhibit stands since the 1960s. When they are gone, visitors will be met by a large hall whose far wall is dominated by a totem pole as high as a two-storey house. Phase two of the development will cost £1.5m, two-thirds of it coming from a National Lottery grant.