Film crews come to Long Island for two things it has that nowhere else within an hour of Manhattan does: an enormous stock of surviving industrial-age mansions, and a coastline that looks convincingly like the end of the world in February.

Both are visitable. That is the part most location round-ups leave out.

The Gold Coast, by the numbers

Starting in the early 1890s, the North Shore filled with the estates of people who had more money than the country had ever produced before. More than 500 mansions went up across roughly 70 square miles, through Great Neck and Port Washington in North Hempstead, Glen Cove, Oyster Bay, and out into Huntington.

About 200 of them survive. That attrition rate is the story of the twentieth century in one statistic: estate taxes, the Depression, and the arithmetic of heating a forty-room house.

What survived did so mostly by becoming something else. Old Westbury Gardens is a museum home. The Vanderbilt Museum, the Nassau County Museum of Art, Planting Fields and the Webb Institute all occupy former estates. The consequence for a film production is a supply of period interiors with parking, insurance and a booking process, which is why the same handful of rooms turn up repeatedly on screen.

Fitzgerald got here first

The Great Gatsby is set on this coastline, and the geography is barely disguised. West Egg and East Egg are fictionalized versions of Kings Point and Sands Point, two real villages facing each other across Manhasset Bay.

That is worth knowing before you visit, because the novel is why the Gold Coast reads as shorthand for American wealth in the first place. Every subsequent production shooting a mansion here is working inside a frame Fitzgerald built in 1925.

Sands Point Preserve, where you can walk into it

The clearest place to see all of this at once is Sands Point Preserve, at 127 Middle Neck Road in Sands Point, which holds three separate mansions on one property: Hempstead House, Castle Gould and Falaise.

The Preserve is open about being part of the production economy. It offers film and television production services directly, and it runs a "Lights, Camera, Hempstead House" tour built around that side of the property. Trails, garden and playground are open Wednesday through Sunday, 9 to 7.

Three mansions on one site, in the village Fitzgerald used for East Egg, is about as concentrated as Long Island's screen history gets.

Eternal Sunshine, and the winter beach

The other Long Island that films well is the empty one. Michel Gondry's Eternal Sunshine of the Spotless Mind, released in 2004, shot over roughly three months beginning in mid-January 2003, which is precisely why the beach scenes look the way they do. That bleached, wind-scoured Montauk is not a color grade. It is Montauk in January.

The beach sequences were filmed at Montauk and near East Hampton. The shot of the ocean taking the house apart was done in camera rather than digitally: the crew built a corner of a house on the beach and let the tide come in.

The Montauk railroad station appears as the place the characters meet again after their memories are erased, which lands differently once you know that the Long Island Rail Road's Montauk terminus is genuinely the end of the line. There is no further east to go by train.

One detail worth having before you plan a pilgrimage: Joel's apartment is described as being in Rockville Centre, but the apartment and the 1950s kitchen were sets built at a former U.S. Navy base in New Jersey. The Long Island in that film is the outdoor Long Island.

The other two worth your afternoon

Old Westbury Gardens, at 71 Old Westbury Road, is 200 acres around Westbury House, with a Walled Garden and a thatched cottage among the formal plantings. It is the closest thing on the island to an English country estate that survived intact, which is exactly the quality a period production is buying. Final admission is 4 p.m. for non-members, so it is not somewhere to arrive late.

The Vanderbilt Museum, at 180 Little Neck Road in Centerport, is a different proposition again: a Spanish Revival mansion built in stages between 1910 and 1936, with a natural history museum and the Reichert Planetarium on the same grounds. It is on the National Register of Historic Places, and it belonged to William K. Vanderbilt II, great-grandson of Cornelius and a genuine pioneer of American motorsport, which is a more interesting biography than the usual heir-with-a-house.

How to actually see any of it

The estates are the easy part, because they are museums and preserves with published hours. Sands Point Preserve, Old Westbury Gardens, Planting Fields and the Vanderbilt Museum all take visitors, and a single day can reasonably cover two of them if you accept that Gold Coast properties are large and the walking is real. Check current hours before setting out; several of these sites run reduced or tour-only schedules outside the summer season.

Montauk is the other kind of trip. Go in the off season if you want what the film has, which is emptiness. The town in August is a completely different place and will not give you the shot.

And a note on courtesy that applies to both: these are working sites. The mansions are staffed institutions with ticket desks, and Montauk is a village of people who live there year round. Neither is a set.