MMDCLX

MMDCLX is the Roman numeral for the year 1666. In historical contexts, it marks events in the mid-17th century, particularly in England and Europe.

The Great Fire of London began on 2 September 1666 and burned for four days, destroying large portions of the City of London. It is estimated to have consumed about 13,000 houses and 87 parish churches, along with numerous civil structures, leaving tens of thousands homeless. The disaster led to a major rebuilding effort that reshaped London's urban plan, with an emphasis on brick and stone construction and wider streets, coordinated by the Commission for Rebuilding London and later associated with architects such as Sir Christopher Wren.

Earlier in 1666, as part of the ongoing Second Anglo-Dutch War, naval forces fought several long battles between England and the Dutch Republic in the North Sea and around the Channel. The conflict disrupted trade and would not be settled until the Treaty of Breda in 1667.

1666 falls within Isaac Newton's annus mirabilis period, during which he made important advances in mathematics and natural philosophy while in seclusion from the plague years. His work during this era contributed to the later development of calculus and classical mechanics.

The year thus stands as a crossroads of disaster and scientific development, highlighting the intertwining of urban catastrophe, military conflict, and scientific progress in early modern Europe.