Every child's grandparents should have a big castle of a house with winding staircases and secret hideways and wood where roosters roam free. Wealthy Baltimoreans Sumner and Dudrea Parker built such a house, which they named "The Cloisters." When they died they left it to the city of Baltimore, which turned it into a children's museum. Now the house, a stone-and-timber Tudor mansion on a wooded hill north of Baltimore, echoes with the patter of little feet on the winding staircases. At the top of the stairs, the kids have a hard time deciding what to do first.

"I want to make a puppet," one child says tentatively.

"We're going in there," another tells her mother.

"But first let's look at the dolls," says the third member of the group.

The dolls, porcelain-faced antiques, are having a tea party in a glass case, and the exquisite dollhouses are not supposed to be played with. But in the next room there's a long table with colored paper, tissue paper, fabric scraps, yarn, crayons and paste, which a pre-schooler and her mother are turning into hand puppets. And in the room after that, which has a play castle and half a dozen hobby horses as well as a lot of musical instruments, a little boy is checking out the xylophone.

"How do you play 'Popeye' on this?" he asks his mother, and when all else fails they both start to sing: "I'm Popeye the Sailor Man . . ."

"Let's go see the bees," suggests the mother, but the two never make it past the rubbing room. Using flat, fist-size crayons, a little girl finishes a rubbing of a Cat's Paw shoe sole, then switches to a marble tombstone dated 1821.

There are car licenses and heating grates to rub, but the irrestible temptation is to wander on, to find out what's in the next room. A big room with wall-to-wall mirrors and trunks full of dress-up clothes bring squeals of delight.

"Mommy, I'm a fireman," says a little boy, tromping around in thigh-high boots.

An older boy puts on a wig and a strapless gown, and his mother snaps a picture and promises to "show it to you when you're twenty years old."

"Let's not lose our real clothes,' says another mother, whose kids have traded sneakers and jeans for high-heeled gold sandals and pink net gowns.

In another corner of the same room, socks with faces pop up onto a puppet stage, growling in an impromptu show. A little boy watches the show a moment, but the third floor beckons.

"I'm going to find a witch upstairs," he predicts.

Instead, there's a reading corner with homey, worn old Oriental rugs to lounge on and an old-fashioned radio to listen to. In another top-floor room, hung with Chinese tapestries, three little girls are standing by the leaded glass windows making a zoetrope, which, the instructions tell them, was one of the earliest ways of making movies. As she draws comic-strip images on a long, narrow strip of paper, one girl explains her plot; "It's about this pincess who lives in a castle with lots rooms, and she has the most beautiful clothes . . ."