He was also one of the designers of the Lydia Duff Gray Hubbard garden in New Jersey which now forms part of the Garden Club of America Collection. But it was between 1933 and 1935 that Ralph was to embark on one of his most ambitious projects, the construction of spectacular gardens at the Rockefeller Center in New York. For 75 years, formal gardens have bloomed on the roofs of the British Empire Building and Maison Française. Hancock's "Gardens of the Nations" emulated the cultural styles of gardens from Holland, France, Italy, and England, where each garden had its very own hostess dressed in themed costume. 3,000 tons of earth, 500 tons of bricks, 20,000 bulbs, 100 tons of natural stone, 2,000 trees and shrubs were delivered by the service elevator or man hauled using a block and tackle up the side of the eleven floors of the building. The garden also required 96,000 gallons of water which was lifted by an electric pump. Hancock was confident that what he had created would allow numerous opportunities for other similar gardens in the US. He declared that "the day of penthouse gardening are over and miles and miles of roof space in every metropolis in this country remain to be reclaimed by landscape gardening". Throughout the project Ralph was in regular correspondence with both John D Rockefeller and Nelson Rockefeller. As well as designing and building the gardens Hancock also ran the "Sky Garden Tour". Visitors were charged a dollar a time. The enterprise did not prove to be profitable and lost approximately $45,000 per year. By 1938 the attraction had closed. The roof gardens at Derry and Toms The gardens at the Rockefeller were visited by Trevor Bowen, the managing director of Barkers of Kensington, which had taken over Derry & Toms, a department store in Kensington, London. Bowen liked what he saw and employed Hancock to create a similar effect in the heart of London. This time Hancock was to build three gardens, each with its own unique style and planting. The gardens were; a Tudor garden with herringbone brickwork, impressive Tudor arches and wrought iron. The Spanish garden complete with palm trees and fountains as well as Moorish colonnades. And a woodland garden, built with a cascade, a river and its very own pink flamingoes. Once again the logistics involved in the construction were impressive. Before planting and