A COMBINATION of remarkable ingenuity and pure fun can be found in two exhibitions at the Stamford Museum and Nature Center: “Visions of Gingerbread III: The Sweetest Architects” and “All Aboard With Bill Probert and Friends II,” each of which demonstrates meticulous planning, design and construction skills.

“All Aboard” fills the museum’s Leonhardt Gallery with a nearly 400-square-foot metropolis built entirely of Lego. Three railroad trains and two monorails activated by motion detectors travel across farmland planted with about 3,000 ears of corn, each consisting of 10 Lego pieces; to and from an airport where several planes are in flight; past a soccer field and campsite (you can see the campers’ dinner roasting on a spit); and around a downtown bustling with shops, cafes, a five-story department store and hundreds of busy figures.

The environment was created by Bill Probert, 52, a Lego enthusiast for the past 20 years, with help from members of Lego fan group: I LUG NY. All are part of the international Adult Fans of Lego community (members call themselves AFOLs).

Mr. Probert said that about 80 percent of the Lego pieces he used in “All Aboard” were no longer available in stores. “Some I bought years ago,” he said, “and others I purchased on the secondary market.” He owns about 2,000 Lego sets, each containing anywhere from 100 to 5,000 pieces.

“Beyond that,” he said, “I have containers and containers all organized into small pieces.” Pointing at one filled with green plastic, he added, “There’s a box of grass, or they could be flower stems.”

Throughout the run of the exhibition, Mr. Probert, who lives in Fairfield, will be making changes to his trainscape, rearranging neighborhoods and their occupants so there will always be something new to see. Look carefully, because he has included lots of unexpected details: a skeleton lying across a train track, an octopus hiding under a bridge, Star Wars characters dueling and other surprises.

The sugary structures in “Visions of Gingerbread,” now in its third consecutive year, are also filled with unexpected, if less durable, details — from a pretzel fence with cinnamon stick posts to a snowman in the shape of a pig. The work of this year’s architects — on view in the gallery adjacent to “All Aboard” — comprises eight ornate gingerbread scenes that are 100 percent edible; one is even labeled “allergen free.” Some of the displays, however, use dough that hardens more than traditional gingerbread, and Rosa Portell, the museum’s curator of collections, said that after five weeks on display, “They would not make for pleasant eating.”

Six of the structures were created by bakeries based in Fairfield County, and two were made by museum staff members. Laura Jason, of Dough Girl Baking Company in Rowayton, placed Santa on a sailboat in her “Holiday at Sea.” Lisa and Stephen Maronian, owners of Sweet Lisa’s Exquisite Cakes, in Cos Cob, built a snow-draped Radio City Music Hall, with a trimmed Christmas tree perched on its ledge. In “Lulu & Pippa’s House on Heckscher Farm,” Beth Strauss, an instructor at the museum’s preschool, recreated the pen on the museum grounds that is home to the two baby pigs. Judges have already awarded first, second and third prizes, but a public vote to choose a favorite is being held through the show’s end, on Dec. 18.

“We realize that people are stressed at this time of year with all the holiday preparations,” Ms. Portell said. “So we plan shows where you can bring the whole family and truly get away. What we say is: ‘Come to the museum, and take a holiday from the holidays!’ ”