Frederik Magnus Piper was an architect active in Sweden in the second half of the 18th century. He studied painting and architecture across Europe. He was particularly interested in English parks and gardens, and made many descriptions and drawings of the landscapes he visited. Piper laid out several parks in the English landscape style in Sweden.
Fredrik Magnus Piper was a nobleman but came from a bourgeois family, his father having been ennobled only in 1776. He studied mathematics and hydraulics at Uppsala University between 1764 and 1766, after which he went on to specialise in engineering in a special school in Trollhättan and at the naval base in Karlskrona. In Karlskrona he befriended Admiral Fredrik Henrik af Chapman, who supported his artistic ambitions. After continuing his studies in Stockholm, partly under the tutelage of the architect Carl Fredrik Adelcrantz, he went on a study trip to the United Kingdom. He left Sweden in 1773, only to return in 1780.
Aided by a letter of recommendation by af Chapman, Piper was introduced to William Chambers and to institutions such as the Royal Academy. During his stay in England, Piper was introduced to the then new theory and practice of English landscape gardens. He made well-executed drawings of The Leasowes, Painshill and Stourhead, and worked for a while at Chambers' firm. He later left England and continued his studies in France and Italy. In France he studied the gardens of André Le Nôtre and in Italy he made visits to the gardens at Villa Lante, Villa Doria Pamphili and Villa Aldobrandini. He returned briefly to England where he married in 1780, and then finally went back to Sweden. Chambers was unhappy that Piper had left England, writing to Admiral af Chapman to complain that he had not been consulted sufficiently. It appears, however, that Piper always held Chambers in high regard as "his first art teacher".
In Sweden he was quickly promoted and given prestigious commissions by King Gustav III, despite having an undiplomatic and overly straightforward demeanour. Most of his work was executed during the reign of Gustav III, who strongly supported Piper. After the assassination of the king in 1792, his activity declined.