Final answer:
Beethoven wrote the majority of his symphonies during the Romantic era, specifically in his Third compositional period.
Step-by-step explanation:
The majority of Beethoven's symphonies were written during the Third compositional period, which is considered the Romantic era. Beethoven's early works were influenced by Classical music, but as he matured as a composer, his music became more emotional and expressive, characteristic of the Romantic style.