Marcus Aurelius (121-180), statesman, philosopher, general, and Roman emperor 161 ??180. As a Stoic, his philosophy on the virtues of wisdom, justice, fortitude and temperance based on reason is outlined in Meditations. This gilded bronze equestrian monument was erected towards the 2nd century CE. Exceptionally this monument survived because it was believed to be of the first christian Roman emperor, Constantine.Later comparison of the facial features, hairstyles etc. of 110 known portraits positively identified this statue to be of Marcus Aurelius. To combat the corrosion caused by nearly 1900 years of air pollution, conservation was started in 1981. Lengthy investigations led to new non-destructive tests followed by non-invasive restoration of the monument. This has provided valuable information for other outdoor bronze monuments.