Scheduled for completion in 2006, the new building will provide almost a 100,000m2 of office space for the Hearst Publishing Corporation.
When completed the new tower will consume less energy than conventional New York office building and is set to become the first commercial office building in New York City to achieve a 'Gold Rating' under the US Green Buildings Council.
Foster said: 'The Hearst tower expresses its own time with distinction, yet respects and strengthens the existing six-story historical structure.
'The tower is lifted clear of its historic base, linked on the outside only by columns and glazing, which are set back from the edges of the site.
'The transparent connection floods the spaces below with natural light and encourages the impression of the new floating above the old,' he added.