Complex sentence: The foundation stone was set on 30 December 1955 by the prime minister (Pibulsongkram) on that date, but the construction stopped for a period of 10 years, until 1968.
Split into simpler sentences: The foundation stone was set on 30 December 1955 by the prime minister (Pibulsongkram) on that date. But the construction stopped for a period of 10 years, until 1968.