 Architect Enos Cooke of New Kensington developed the plan for the church building . In 1940 , a friend of the church , John Stanish , informed Mt . St. Peter 's congregation that the Mellon mansion , 6500 Fifth Avenue , in Pittsburgh , Pennsylvania , was to be demolished . Stanish had worked for the three Mellon brothers until the last of them died in 1938 . The Mellon family had spent years entertaining important people , including royalty , celebrities , well known financiers , and statesmen in the Mellon Mansion . It was built using Michigan sandstone and was four stories high on one side and three stories high on the other . The mansion had sixty @-@ five rooms , plus halls and vestibules . There were 11 bathrooms , one of which had cost over $ 10 @,@ 000 to complete because the walls and floor were covered in Italian marble and the fixtures were plated in gold . At one time , a hundred servants had maintained the house and surrounding grounds . The mansion had been completed in 1909 and had cost Mr. Mellon approximately three million dollars . The inside was filled with marble from all over the world , including China , Japan , and India . There were bronze doors cast in England , hand painted ceilings , and steel beams manufactured by the Carnegie Steel Company . In addition , one of the most expensive organs in the world was housed in this building . The items which the mansion contained were being sold for less than their actual values . For example , a half a million dollars worth of furniture had been sold for $ 3 @,@ 800 . The building contained many items that could easily be used in a church . There were mantles that could become altars and pieces of architecture , such as angel statues , that could be placed in Mount St. Peter Church . In 1940 , St. Peter 's congregation bought all of the stone , granite , marble , bronze doors , and railings from the mansion . In addition , the congregation purchased thirty tons of steel beams , sixty @-@ five oak doors , chandeliers , and some other items , and the members transported all of the marble 27 miles ( 43 km ) from Pittsburgh to New Kensington . The location of the mansion is now home to Mellon Park . 
