Complex sentence: The original plat of Galveston, drawn in the late 1830s, includes Avenue B, but the origins of its nickname-- "the Strand"--are unknown; some have speculated that it was named after the well-known Strand street in London.
Split into simpler sentences: The original plat of Galveston, drawn in the late 1830s, includes Avenue B, but the origins of its nickname are unknown. Some have speculated that it was named after the well-known Strand in London.