In 1853 the Society began plans for the new museum building by applying for a grant from the Treasury, partly in compensation for the building the RDS had handed over to Board of Trade which was to become the New School of Design. A grant of £5000 was granted, with £2500 to be raised by public subscription. This resulted in the building which still houses the Natural History Museum today. It was originally built as an extension to Leinster House, where the Royal Dublin Society was based from 1815 until 1922. The building was designed by architect Frederick Clarendon in harmony with the National Gallery of Ireland on the other side of Leinster Lawn. The frame of the building is cast iron, largely clad internally with timber on the upper floors. The exterior uses dressed granite and Portland stone. The foundation stone was laid on 15 March 1856 by Earl Carlisle the Lord Lieutenant of Ireland, and the building was completed in 1857 by contractors Gilbert Cockburn & Son. It was connected to Leinster House by a curved closed Corinthian colonnade, which once held displays of the Geological Survey of Ireland. The connection of the buildings allowed a visitor to move from Leinster House to the Museum building, and was eventually connected with the purpose built museum on Kildare Street.