From the earliest barrels made by winding straps of iron around a mandrel, cannon barrels have been "built up."
Essentially you want a cannon barrel to do two mutually incompatible things. The bore has to be hard & durable enough to withstand the charge & passage of the round. The surrounding metal has to be able to absorb the stress of both.
An example from the civil war is the Parrott & Wierd rifles with built up breeches.
en.m.wikipedia.org
In the latter half of the 19th & into the 20th Century an improbable but highly effective process was used. A sleeve was wrapped in up to hundreds of miles of wire. The last use of that technique was in the enormous 18" cannons for the Imperial Japanese super battleships Yamato & Musashi.
Given its age, the howitzer barrel pictured in this thread was built up. A hollow cylinder of hot metal was slid over a sleeve. The surface would have been forged to make it hard as the cooling metal in the center would remain elastic.
The modern day practice for period cannon is drilling out an aluminum casting or reboring period iron guns & pressing a steel sleeve in place is the standard.
The much less expensive, but problematic, practice of casting around the sleeve was demonstrated by the failure of a cannon at Fort McHenry.
Link:
failure of cannon ft mchenry
The Trafalgar Gun Company in England uses a fiberglass shell that surrounds up to eight compressed gas guns for movies & celebratory firings.
As at Fort Defiance in Clarksville TN fiberglass is a very effective substitute for large caliber display cannon.
I highly recommend the link below that documents the evolution of artillery barrel construction:
Artillery - Breech-Loading, Gunnery, Cannons: In 1854 William Armstrong, an English hydraulic engineer, designed an entirely new type of gun. Instead of simply boring out a solid piece of metal, Armstrong forged his barrel from wrought iron (later from steel). He then forged a succession of...
www.britannica.com