Mallet's Mortar

Recently I visited Fort Nelson, just outside Portsmouth, England and saw this monster.

This is one of two Mallet's Mortars, built but never fired in anger in the 1850's. It stands over 2 metres tall. Built in parts for easy transportation, it fired a shell weighing 1000 - 1300 kg over a distance of 2500 metres. This example was never fired.