Caesarsboom (Caesar's Tree) is a very old tree whose precise age is unknown but is believed to be over 2000 years in age. The ancient tree grows in Lo, a town in Lo-Reninge, a municipality of the province of West-Vlaanderen of Belgium. Its species is Taxus baccata, common name European Yew. The tree is designated a national monument of Belgium.
According to a long-held local legend, Julius Caesar stopped at this tree during his military campaign in the area en route to Britannia in 55 BC, tied his horse to it, and took a nap in the shadow of its foliage. According to one source, although the road passing by the tree might date from the era of Imperial Rome, it is not likely that Julius Caesar came to this area.
The tree grows beside the last extant city gate, of four medieval arches built in the 14th century (and restored both in 1852 and 1991); at the time the town was less than 400 meters in diameter. Caesarsboom stands adjacent to a house called "Het Damberd" ("The Draught-board House") which written sources from 1499 show once housed the oldest of the four breweries which used to exist in the town of Lo. 
- Virtual Tourist: Reninge Travel Guide
-  Flags Of The World website: Lo-Reninge (Municipality, Province of West Flanders, Belgium)
-  A Short Guide to Lo
- Walking the Walls: Kent County Council, le Syndicat Mixte de la Côte d'Opale and the Province of West Flanders Archived 2006-03-10 at the Wayback Machine.
- "Cycling Belgium's Waterways". Archived from the original on 2008-07-05. Retrieved 2008-09-05.
- Website van V.V.V. Lo-Reninge vzw: Westpoort en Caesarsboom Archived 2008-09-20 at the Wayback Machine (in Dutch)
-  Archived 2008-08-18 at the Wayback Machinede Westhoek, pure vakantieland (in Dutch)