Described by experts as "amongst the very best statues surviving from Roman Britain", the sculpture dates to the 1st or 2nd century AD.
The rare piece was found from the site on the Minories, a street in the City of London, close to the Tower of London.
It was uncovered by Museum of London Archaeology (MOLA) experts before the site's redevelopment into a hotel.
The team was at first hesitant to announce the discovery and to proclaim its Roman origins, owing to its almost unbelievable preservation.
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Some 65cm tall and 55cm wide, the sculpture is made from Oolitic limestone from the Cotswolds. A well-known and celebrated school of Romano-British sculptors worked in the area but to date examples of their exquisite work has been scant and fragmentary.
Depictions of eagles and serpents are typically Roman but the closest comparison to this sculpture comes from Jordan, the museum said in a statement.
The symbolism is understood as the struggle of good, the eagle, against evil, the snake. This theme is common in funerary contexts and an important Roman cemetery is known to have been located on the site.
The lack of weathering on the statue corroborates this theory, as does the absence of detail on the back of the sculpture; suggesting it once sat it an alcove.
The object will now be on display for 6 months at the Museum of London.