Complex sentence: The second-tallest building is 360 Condominiums, which stands tall and was Austin's tallest from 2008 to 2010; this is followed by the Frost Bank Tower, which was Austin's tallest structure from 2004 until 2008.
Split into simpler sentences: The second-tallest building is 360 Condominiums, which stands and was Austin's tallest from 2008 to 2010. The third-tallest building in the city is the Frost Bank Tower, which was Austin's tallest structure from 2004 until 2008.