this beautiful married lady. Calton Hill was the location of the notorious Calton Jail, a complex comprising a Debtors' Prison, the Bridewell (1791–96) by Robert Adam (later replaced) and a Felons' Prison of 1815-17 by Archibald Elliot. The prisons were replaced by Saughton Prison and demolished in 1930 providing a site for St. Andrew's House, home to Scotland's senior civil servants. The sole surviving building is the castellated and turreted Governor's House by Elliot. The lower curtain walls of the prison are still visible on the south side of St. Andrew's House, above Calton Road. The eastern end of the ornate Regent Bridge is built into the side of the hill, crossing a deep gorge (at the bottom of which the opening scene from Trainspotting was shot) to connect the hill with Princes Street, now Edinburgh's main shopping street. The engineer in charge of building Regent Bridge in 1815 was Robert Stevenson, grandfather of the author Robert Louis Stevenson. By the 1840s, a pipeline ran over the shoulder of Calton hill from the Edinburgh coal gas works on the Royal Mile at New Street to the Bonnington Chemical Works in Bonnington. The gasworks waste was pumped through the line and processed into useful products at Bonnington. The renowned Scottish architect William Henry Playfair was responsible for the elegant thoroughfare that encircles the hill on three sides. Comprising Royal Terrace, Carlton Terrace and Regent Terrace, the largest of the townhouses can be found on Royal Terrace. Playfair's plan is dated 1819 and the first house was built at what is now 40 Royal Terrace. Regent Gardens that cover over one half of the summit of the hill are privately administered by a local association. Carlton Terrace was originally called Carlton (or Carleton) Place but changed in 1842 to fit in with the other Terraces. Most of the properties on the terraces are occupied as houses but on Royal Terrace there is a number of hotels, by far the largest being the Crowne Plaza Hotel while on Regent Terrace is located the United States Consulate. Royal Terrace with its views over Leith and the Firth of Forth was popular with early owners who were shipowners and traders in Leith. Some of these were involved in the whisky trade, Leith being a centre for whisky blending and storage, and for a time in the 19th century the street was known as Whisky Row.