WHERE: Monticello's new Thomas Jefferson Visitor Center is basically a pressure valve, meant to hold back the crowds from overwhelming the small and fragile 18th-century house it serves.

It also educates and entertains, feeds the mind and the body (at a new cafe), and of course you can shop for Jeffersonian paraphernalia.

But the success of the structure — which opened Wednesday — lies in its separation of functions, and the freedom to avoid any or all of them while waiting for a timed entry to the old house up the hill.

Five rectangular buildings surround a pleasant courtyard that serves as a roof over the lower level of the complex — a layout that allows Monticello's visitors to set their own agenda.

The children's rooms are set apart from the main courtyard, which keeps adult areas a little more calm and reflective.

The cafe is set off at one end, well lit by natural light, with outdoor seating that will be inviting in summer.

But if your primary interest is Jefferson's house, you can easily pass through the courtyard to where a shuttle transports visitors up the hill to see it — a set-up that balances visitor demand with the modest size and delicacy of the old home.

ARCHITECTURAL NOTE: The architects of the new $43 million center have been scrupulous about the design.

A bold, contemporary building might overwhelm Jefferson's house. But a timid or apologetic effort would look and feel cheap. Something made of brick, in the style of Monticello, could be labeled fake and derivative. But any sharp contrast of styles would be out of context.

Using wood and fieldstone, the building feels materially connected to the time of Jefferson. It is also designed as an environmentally sensitive space with green roofs, geothermal heating and cooling, and natural light.

Jefferson was committed to two ideals that matter in domestic space: beauty and convenience.

The challenge was to strive for the pragmatic side of the Jeffersonian ideal: Keep it simple, keep it honest, give people choices, and use creativity to solve problems, rather than try to say something new with the architecture.

IF YOU GO: Monticello is just outside Charlottesville, Va., about 125 miles southwest of Washington, D.C.

The house, gardens and visitor center are open 8 a.m. to 5 p.m. daily, March to October; 9 a.m. to 4:30 p.m daily, November to February (not Christmas).

Tickets: $20 general ($8 ages 6-11). 434-984-9822, http://www.monticello.org.