British Museum | Museum of Modern Art | Metropolitan Museum of Art | American Museum of Natural History | Victoria and Albert Museum | Natural History Museum | San Francisco Museum of Modern Art | Honolulu Museum of Art | museum | Whitney Museum of American Art | Museum of Fine Arts, Boston | Los Angeles County Museum of Art | Solomon R. Guggenheim Museum | National Air and Space Museum | Brooklyn Museum | National Baseball Hall of Fame and Museum | Hermitage Museum | National Museum of Racing and Hall of Fame | Museum of Contemporary Art | Field Museum of Natural History | Philadelphia Museum of Art | Imperial War Museum | Smithsonian American Art Museum | National Museum | National Museum of Natural History | Museum of Fine Arts, Houston | Denver Art Museum | Cleveland Museum of Art | Museum of Contemporary Art, Los Angeles | National Maritime Museum |
In Brecknock Museum a metal electrotype of his 1848 plaster sculpture, Death of Tewdrig, depicts the dying fifth-century king Tewdrig and saint of Glamorgan.
Giardelli’s work is held in many collections including the Tate, the National Museum of Wales, the National Library of Wales, Contemporary Art Society of Wales, Arts Council of Wales, Museum of Modern Art Wales, Brecknock Museum, Tenby Museum and Art Gallery together with museums and galleries in New York, Dublin, Nantes, Bratislava and Prague.