Perhaps it's time to ascend to Fort Jefferson's terreplein via this, the winding staircase at the fort's northern end! As were many American forts built in the mid-19th century, Fort Jefferson was originally conceived as a three-tiered monster...but very few of those three-tier plans ever came to full fruition (Fort Point at San Francisco may have been the only one to make it all the way to three tiers), and as a result there are a series of semi-finished one- and two-tier forts dotting the eastern and Gulf coasts of the United States. In Fort Jefferson's case, once they had built up to two tiers, 'twas revealed a great deal of settling: The fort was essentialy sinking into sandy Garden Key. The engineers were able to solidify the island enough to support two tiers, but a third would have spelled disaster...and so they contented themselves with just the two.