The Casina Pio IV (or Villa Pia) is a patrician villa in Vatican City which is now home to the Pontifical Academy of Sciences, the Pontifical Academy of Social Sciences and the Pontifical Academy of St. Thomas Aquinas. The predecessor of the present complex structure was begun in the spring of 1558 by Pope Paul IV in the Vatican Gardens, west of the Cortile del Belvedere. Paul IV commissioned the initial project of the 'Casina del Boschetto', as it was originally called, from an unknown architect; the first mention of the single-storey building can be found on 30 April 1558, and a notice of the following 6 May, says that the Pope spent "two thirds of his time at the Belvedere, where he has begun to build a fountain in the woods".