Riedel's first project was the supervision of the new development of the Ludwigstraße Damenstift (convent) in Munich. This was followed by the residence and palace garden for King Otto of Greece in Athens, where he was court architect until he returned to Munich in 1850. Here he completed the Propylaea jointly with Leo von Klenze. From 1852 until 1857, Riedel was a professor at the polytechnic institute. In 1853 he was appointed superintendent of the royal building authorities and in 1872 he became the leading court architect.
His works include the Wolfram von Eschenbach Monument in Wolframs-Eschenbach, numerous fountains in the garden of Schleissheim Palace, the Beamtenreliktanstalt and Bavarian National Museum in Munich, as well as numerous drafts and concepts such as for the Cistercian monastery in Mehringen, a new university and a coin. He was also responsible for the restoration of numerous palaces.
Riedel died on 24 August 1885 in Starnberg.
- 1848–64: Concepts for the grave of Maximilian II of Bavaria
- 1849-51: Reconstruction of Berg Castle on Lake Starnberg
- 1852–53: Completion of the Casino on the Roseninsel in Lake Starnberg
- 1852–77: Concepts for the front of the Maximilian-II-Kaserne in Munich
- 1854–56: Extension of Leo von Klenze's bazaar building at Odeonsplatz, Munich
- 1856–58: Reconstruction of Herzog Max Castle in Munich
- 1857: Royal hunting house near Ettal
- 1859–63: Bavarian National Museum, now housing the State Museum of Ethnology in Munich
- 1861–63: Concepts for front of the Neue Kaserne (New Barracks) in Regensburg
- 1862: Concepts for gardens of Feldafing Palace
- 1862–63: Concepts for new university at Karlsplatz in Munich
- 1863–65: Beamtenreliktanstalt in Munich
- 1864: Mausoleum for Maximilian II in Theatine Church, Munich
- 1869–1874: Concept for Neuschwanstein Castle