Most of the creations spring from the minds of builders with adult-size appetites for Lego clicking, often without any instructions. BayLUG President Russell Clark, 33, says 75 percent of the 50 or so members use their imagination and mad Lego skills to piece together their creations. "Very little of it is from stock kits that you'd buy from a store," says Clark, who recently built a replica of Coit Tower.

Clark was an avid Lego-phile until he became a teenager and abandoned the hobby in favor of typical adolescent pursuits. It's a period he refers to as "the dark ages." In college Clark rekindled his love of Lego after seeing a bulletin board item about a Lego club. "It was all downhill from there," he says.

Because he doesn't have space in his apartment to turn a room over to his Lego creations, Clark keeps most of his in storage. The club's monthly shows, such as the just-opened "Living LEGO-cy" at the Museum of American Heritage in Palo Alto, give him and other club members a chance to introduce the highest form of Lego building to the unwashed masses.

The centerpiece of Living LEGO-cy is a 12-by-25-foot Lego train layout depicting the San Francisco waterfront to the Golden Gate Bridge. While not everything in that landscape is included, club members did manage to include the aforementioned Coit Tower, some Victorians, the cable car barn and even some cable cars to go into it.

The heart and soul of a Lego train set lies in the Lego engine brick that picks up power from metal rails that conduct electricity. Unlike HO scale and other miniature train sets with locomotives that can cost as much as $2,000, a Lego engine can be swapped out of one train and put into another in a matter of minutes. If it falls off the track and breaks apart, putting it back together is literally a snap.

Aside from being astounded that Lego has such potential, many first-timers also want to know where they can get their hands on a train set like the ones the club uses. Unfortunately, the Lego brain trust in Denmark has discontinued these sets in favor of a line without metal tracks that will be coming out next year. But, that's not stopping BayLUG - Clark and his colleagues have unopened boxes of train parts.

11-4 p.m. Fri.-Sun. Through Jan. 11. Free. 351 Homer Ave., Palo Alto. (650) 321-1004. www.moah.org.

- Paul Kilduff, 96Hours@sfchronicle.com

This article appeared on page G - 40 of the San Francisco Chronicle