 Possibly the largest prefabricated cast iron structure is the Bulgarian St. Stephen Church in Istanbul, shipped out from Vienna in the late 1890s.The use of decorative cast iron as railings, fences and balconettes then gradually gained popularity in Regency Britain and post-Napoleonic France as a cheaper alternative to the wrought-iron railings that only the wealthy could afford.The idea was exported to the colonies of both countries with hot climates as porches or verandahs, where it formed both decoration and structure.