Animal rights campaigners have staged a protest against Cambridge University's plans for an animal laboratory.
Plans for the laboratory were originally put forward in May 2000
The lab would conduct tests for diseases such as Alzheimer's and Parkinson's on monkeys and other primates.
About 500 people attended Saturday's demonstration at the proposed site.
Plans for the controversial lab, proposed for an area of green belt land near Girton on the outskirts of Cambridge, are yet to be approved by the office of the deputy prime minister.
Earlier, Professor Tony Minson, from the university, said the lab would provide suitable facilities needed for the "kind of research that we're convinced will make really serious contributions to diseases that are so damaging to so many families and so many people".
The demonstrators, he said, should remember that "they and their families and their children have benefited enormously from medical research using animals."
Professor Minson said there was a possibility they would deny "similar benefits to future generations" by preventing the lab from being built.
Research would be conducted into Alzheimer's, Parkinson's, schizophrenia and manic depression, and other neurological diseases.
But the director of animal rights organisation Animal Aid, Andrew Tyler, said the suffering of the animals was "considerable".
"It's about opening up monkeys' brains, destroying parts of the brain with chemicals and surgery," he told the Today programme.
He said scientific evidence questioned the suitability of using monkeys for such research.
"[Our] evidence demonstrated conclusively that yes, it's a laudable aim and we all want remedies for these devastating conditions, but the monkey is an impossibly poor model."
Plans for the £20m laboratory, first proposed in May 2000, are still awaiting government approval.
An internal university report has claimed university authorities did not give a full picture when the plans were first put before the university's own governing body, the Regent House.
The report by the Board of Scrutiny, the university's official watchdog, claimed the extent of animal experiments at the site was kept hidden.
As a result it said, the Regent House passed the plan without knowing the full details.