From 1820 to 1890 was how many decades?
20s, 30s, 40s, 50s, 60s, 70s, 80s.
Classical Era (1750 - 1820) The Classical period has been called the "Golden Age of Music" because it was at this time that the major forms of Classical music were fully developed. The classical era runs roughly from the 1750s into the early decades of the 1820s. The main composers of this era are Bach, Beethoven, Cimarosa, Clementi, Diabelli, Haydn, Mozart and Turk.