Complex sentence: Bodega Bay is the site of the first Russian structures built in California, which were built in 1809 by Commerce Counseller Ivan Alexandrovich Kuskov of the Russian-American Company in the lead-up to the establishment of Fort Ross.
Split into simpler sentences: Bodega Bay is the site of the first Russian structures built in California. These were built in 1809 by Commerce Counseller Ivan Alexandrovich Kuskov, of the Russian-American Company in the lead up to the establishment of Fort Ross.