Complex sentence: The Feast is held at modern-day Fort Ouiatenon, on the Wabash river which is a replica of Fort Ouiatenon which was the first fortified European settlement in what is now called Indiana.
Split into simpler sentences: The Feast is held at modern-day Fort Ouiatenon, on the Wabash river. The facility is a replica of Fort Ouiatenon which was the first fortified European settlement in what is now called Indiana.