Google antique shops. Take a few photos and send them on. Unless it’s it’s in prime condition you’ll either get “not for us, thanks” or no replies.
After that, DoneDeal or Adverts. But you’d be unlikely the get “antique” prices.
There might be a salvage yard near you that would be interested (going by your username http://www.royalsalvage.com/Welcome.html might be near). They're unlikely to offer you a lot for it though.
Landmark Architectural Salvage and Granite Products is Ireland's newest architectural salvage company specialising in the supply of top quality products, old and new from around the world, most importantly, sourced here in Ireland.