Complex sentence: The Trades Hall is one of the oldest buildings of Edwardian architecture found in the city of Johannesburg with historical and heritage significance.The building used to be the headquarters of the Trade Unions and it also saw many historical events such as the the 1922 Rand Revolt.
Split into simpler sentences: The Trades Hall is one of the oldest Edwardian buildings in the city of Johannesburg. It was associated with many historical events such as the the 1922 Rand Revolt.