Visit the Artery during the day, and it looks at first glance like an enclave for a neighborhood crack dealer. Surrounded by a dense thicket of hackberry trees and a rusting chain-link fence, the lot in the Museum District's residential area is full of rubble. Indeed, works by artists such as Louise Bourgeois and Frank Stella are much more likely to turn up a few blocks away at Houston's more famous sculpture enclave, the Cullen Sculpture Garden. But just as the sun sets and the Cullen goes dark, the Artery comes to life. The rubble -- loads of stone construction materials left on the lot by the previous owner -- takes shape as a series of intricate light sculptures set along winding, wooded paths. You'll find beakers bubbling over with smoke, illuminated ductwork weaving through patterned stacks of slate, and a fireplace enlivened by a fan, a light bulb and fluttering red cellophane. The mastermind behind the Artery, Houston artist Mark Larsen, has opened it to the public for talks and performances since 1987 -- and always free of charge (though donations are appreciated). Veteran patrons might want to check out the newest exhibit: burnished tree branches, half sculpted, half wild, that are bound in rope, blending in with the Artery's natural environment, yet jarring to the senses like captured beasts from a foreign jungle.