known as Big Ben, was raised as a part of Charles Barry's design for a new Palace of Westminster, after the old palace was largely destroyed by fire on 16 October 1834. Although Barry was the chief architect of the neo-gothic palace, he turned to Augustus Pugin for the design of the Clock Tower, which resembles earlier Pugin designs, including one for Scarisbrick Hall in Lancashire. Construction of the tower began on 28 September 1843. The building contractors were Thomas Grissell and Morton Peto. An inscribed trowel now in the Parliamentary Archives records that Emily, sister of Peto's daughter-in-law, was given the honour of laying the first stone. It was Pugin's last design before his descent into mental illness and death in 1852, and Pugin himself wrote, at the time of Barry's last visit to him to collect the drawings: "I never worked so hard in my life for Mr Barry for tomorrow I render all my designs for finishing his bell tower and it is beautiful". Design Completed in 1859, the tower is designed in Pugin's Gothic Revival style, and is high making it the third tallest clock tower in the UK. Its dials (at the centre) are above ground level. The tower's base is square, measuring on each side, resting on concrete foundations thick. It was constructed using bricks clad on the exterior with sand-coloured Anston limestone from South Yorkshire, topped by a spire covered in hundreds of cast-iron rooftiles. There is a spiral staircase with 290 stone steps up to the clock room, followed by 44 to reach the belfry, and an additional 59 to the top of the spire. Above the belfry and Ayrton light are 52 shields decorated with national emblems of the four countries of the UK: the red and white rose of England's Tudor dynasty, the thistle of Scotland, shamrock of Northern Ireland, and leek of Wales. They also feature the pomegranate of Catherine of Aragon, first wife of the Tudor king Henry VIII; the portcullis, symbolising both Houses of Parliament; and fleurs-de-lis, a legacy from when English monarchs claimed to rule France. A ventilation shaft running from ground level up to the belfry, which measures by , was designed by David Boswell Reid, known as "the grandfather of air-conditioning". It was intended to draw cool, fresh air into the Palace of Westminster; in practice this did not work and the shaft was