Due north of the house on top of Penielheugh is the most important architectural feature of the Monteviot estate. It is a huge stone Doric column over 150 feet high erected by the 6th Marquis of Lothian to commemorate the Duke of Wellington (to whom he was related through his mother), and the Battle of Waterloo following the defeat of Napoleon. This stupendous local landmark represents the second attempt on the site by the 6th Marquis. The first, a pyramid built in 1815 to the design of William Burn fell down ‘with a tremendous crash’ only a year after construction. The existing monument in the form of a ‘Triumphal Column’ was designed by Archibald Elliot and begun in 1817. It took 10 years to build, the stone being quarried locally. The inscription inlaid in letters of lead on the base reads:
‘To The Duke of Wellington And The British Army William Kerr VI Marquess of Lothian And His Tenantry Dedicate This Monument XXX June MDCCCXV’ The wooden gallery and picturesque spirelet on top were added by the 8th Marquis in 1867, to the design of John Hungerford Pollen, the Pre-Raphaelite architect. There is an internal spiral staircase which gives access to this elevated viewing platform.