Portland Head Light has been burning since January 1791, commissioned by George Washington and paid for by a young federal government that had barely finished writing its own constitution. It stands on Cape Elizabeth's rubble ledge at the mouth of a harbor that once shipped more tonnage than Boston. Casco Bay is the reason. The bay's Calendar Islands — traditionally counted as one for every day of the year, actually numbering around 200 — form a drowned landscape of long, parallel ridges scraped by glaciers and flooded when the ice withdrew. Those ridges made superb sheltered anchorages and appalling navigation. Ledges lie inches beneath the surface at high water. Fog arrives without ceremony. The result was a nineteenth-century building programme in stone and cast iron: Spring Point Ledge Light, planted directly on a submerged shoal in 1897 to spare coasting schooners the reef off Fort Preble; Ram Island Ledge Light, its granite tower finished in 1905 after the liner Californian tore herself open on the rocks; Bug Light at Bug Light Park, a small Greek Revival oddity modelled on a Corinthian monument in Athens. Sail carried all of it. Portland's wharves were built for schooners hauling lumber, granite, ice and salt cod, and the two-masted coasting schooner was the working truck of the New England seaboard well into the twentieth century. A portland schooner lighthouse cruise retraces that commercial geography under the same rig — gaff-headed sails, wooden blocks, a hull that heels rather than pounds. The vessels working from Maine State Pier today are pleasure craft, but the sailing is real: engines off where wind allows, crew hauling halyards by hand. What survives is unusually intact. Fort Gorges, a granite hexagon completed in 1865 and obsolete before it was armed, still squats on Hog Island Ledge. The Portland Observatory of 1807, on Munjoy Hill, remains the last maritime signal tower in the United States. Around them the working harbor continues — draggers, tugs, the Nova Scotia ferry — so that Casco Bay lighthouse cruise passengers read the coastline as a functioning system rather than a museum. That legibility is the argument for going out on the water. From Commercial Street the lights are separate postcards; from a deck two miles offshore they resolve into a single chain of warnings, each answering a specific hazard. Portland schooner lighthouse cruise tours, departing daily between 09:00 and 20:30 from 56 Commercial Street, are the closest most visitors will come to seeing the bay the way its builders did.