Peter Parler was a famed gothic sculptor and architect, who lived in worked in the mid to late 14th century CE.
Parler was born into a virtual dynasty of stonemasons - the surname itself is derived from Parlier, German for "stonemason" - in the year 1330 CE, in the town of Schwabisch-Gmünd (in present-day Germany.) Details of his early life are somewhat lacking, but it is known that he learned about sculpting, structural engineering, and architectural design (a stonemason was more an engineer than a simple craftsman) in his family's workshops. He was evidently a quick study, as at age 23 (in 1353) he was called to the new imperial capital at Prague by the emperor Charles IV. There, he took up work on St. Vitus Cathedral, as its original architect - Mathias of Arias - had died the previous year, only eight years into the cathedral's construction. Parler was responsible for most of the design elements of the building, despite the fact that it wasn't truly finished until 1929, including most of its beautiful gothic architecture and flying buttresses.
Prague's first stone bridge - the Judith bridge across the Vltava River, built in 1170 - was destroyed by violent floods in 1342. The emperor, impressed with Parler's competence, commissioned him to build a replacement; construction began in 1357. The result is the spectacular Karluv Most, or Charles Bridge, a 516m span that is 10m wide and rests on 16 massive pillars - quite an engineering feat for the time.
Parler continued his work for Charles IV throughout his life, overseeing the construction of St. Vitus and undertaking other projects as well. In 1380 he began work on another cathedral, St. Barbara's, this time in the nearby town of Kutna Hora. This project also lasted beyond Parler's lifetime, although it took only two centuries to St. Vitus' six. He also undertook the remodelling of a building called the Italian Court, which had been founded in 1300 as a mint. Architecture was not his only forte, either - he was responsible for a number of sculptural works, although few now remain. Most notable are a pair of busts in the triforium of St. Vitus - a self-portrait, and a rendition of his patron emperor.
Parler founded a thriving workshop that did work on numerous other projects in the coming years, including the church of St. James. In addition, his son John took after his father and went on to construct the beautiful Imperial residence in Kutna Hora, a favorite of the emperor. In 1399, Peter Parler passed away in Prague, the city most enriched by his brilliant work. If you're ever in the area, it's well worth your time to stop and see some of it.
Some images of Parler's busts can be viewed at the Web Gallery of Art's "Peter Parler" page, at http://www.kfki.hu/~arthp/html/p/parler/index.html. Additionally, the LAVA Architectural Guide and Gallery has an excellent photo tour of St. Vitus Cathedral, at http://lava.ds.arch.tue.nl/gallery/praha/thrad_sv.html.
I used information from the Parler genealogy sic website, Arthur Frommer's "Kutna Hora," the Web Gallery of Art's entry on "Peter Parler," CZ EuroTour's article on Prague, and Xrefer.com's entry on "Peter Parler" in the preparation of this summary.