Pfizer's giant research base at Sandwich, southern England, has been officially put on the market by CB Richard Ellis, according to Reuters. U.S.-based Pfizer in February decided to close the site.

The commercial real estate services firm said it would market the 3 million-square-foot site, where Viagra was invented, under the new name "Discovery Park."

The name reflects the hope that at least some of the buildings at the facility, which employs 2,400 people, will continue to be used for research work.

Sandwich is Pfizer's biggest R&D facility in Europe and the largest R&D site of any foreign-owned drug maker in Britain. It has been a base for medicine discovery for Pfizer since 1954.

Finding new tenants interested in continuing the site's work in pharmaceutical research is unlikely to be easy, given over-capacity in drug R&D worldwide that has led to a number of similar closures by other companies.