What's the must-see thing in Key West?

Fort Zachary Taylor sits at the southwest corner of the island, about a 15-minute walk from Duval Street. The park charges $6 per person for walk-ins and $4 for cyclists. The fort dates to 1845, and the Union held it through the entire Civil War without a Confederate assault. The beach along the south shore is Key West's best. It is the island's only beach with natural coral sand rather than trucked-in fill. The water runs clear enough to snorkel straight off the shore, and the rocky bottom near the seawall holds parrotfish and sergeant majors within 20 feet of the sand. By 8:30am the water temperature sits around 29°C in summer, warm enough to make you forget you are standing on a military fortification. The coral rubble along the entry will cut bare feet fast, so grab reef shoes from any shop on Duval Street before heading over.

The Ernest Hemingway House at 907 Whitehead Street costs $18 for adults and runs 30-minute guided tours every 15 minutes from 9am to 5pm. The building is a limestone block house from 1851, and about 60 polydactyl cats still roam the grounds, descendants of a six-toed cat a ship captain gave Hemingway in the 1930s. You will smell them before you see most of them. The writing studio sits above the carriage house in the back garden, reachable by a catwalk Hemingway had built so he could cross from the second-floor bedroom without going downstairs. The pool in the backyard cost $20,000 when Hemingway installed it in 1938, making it Key West's first residential swimming pool. He told Pauline she might as well take his last penny, and a cent is still pressed into the concrete beside the pool deck.

The Southernmost Point buoy on the corner of Whitehead and South Streets marks 90 miles to Cuba, though the claim is slightly generous since the actual southernmost land in the continental US is a fenced naval air station next door. The buoy went up in 1983. The line for a photo runs 15 to 45 minutes long when cruise ships are docked at the Mallory Square terminal, which happens most days between 8am and 5pm during high season, November through April. Come at 7am or after 6pm and you might wait 2 minutes. To be fair, the photo itself takes 10 seconds. Whether that is worth a half-hour wait is your call, but the walk down Whitehead Street from the Hemingway House covers 6 blocks and passes wooden houses from the 1830s and 1840s, several with historical-registry plaques on their front gates.

Skip Mallory Square's sunset celebration on your first evening if you are tired from traveling. The performers and food vendors start around 5pm, but the crowd packs the waterfront 3-deep by 6:30pm, and the sunset looks the same from any west-facing bar on the island. The Waterfront Brewery on William Street or the rooftop at El Meson de Pepe both face due west with a fraction of the crowd. Key West is 2 miles wide and 4 miles long. You can walk the entire Old Town in a morning. That small footprint means the must-see list is short, and the worst first-day mistake is cramming too many stops in when September temperatures hover near 32°C with 80% humidity.