The Glass House, a National Trust Historic Site picturesquely situated in New Canaan, throws a party every summer. The annual fundraiser offers guests a picnic with champagne and chance to stroll around the museum's grounds, savoring a taste of early summer.

This year, several local businesses are returning as sponsors of the Summer Party event, the proceeds of which go to the upkeep of the house. Design Within Reach in Stamford; Callari Auto Group and Espresso Neat in Darien; Elm Restaurant in New Canaan; and Chris Durante Framing Studio in Danbury are some of the businesses joining a list of illustrious national sponsors, like Ralph Lauren and Swarovski, in support.

"We have great relationships with our sponsors and they equally show their support to the Glass House," said Christa Carr, a spokesman for the Glass House. "We strongly believe in community outreach and supporting our local community."

For local sponsors, the event is a chance to broaden their exposure in the community. Chris Durante, owner of the eponymous framing studio, said the event is a chance to exchange in-kind services. Durante provides the framing for the donated artwork that goes on sale during the event. In turn, being a part of the party gives Durante a chance to showcase his business and benefit a local landmark.

"It's a great cause," said Durante, who participated in the event last year as well. "It helps me promote my business a little bit and it supports a great institution."

Espresso Neat in Darien will send two staff members to the Glass House party, as it did last year.

"They just reached out to us and we decided to partner up," said Rachel Haughey, owner of Espresso Neat. "It's a lovely event."

The Glass House is a 49-acre site designed by Philip Johnson, which celebrated its public opening with an inaugural picnic in June 2007.

The Summer Party is open to the community, and 300 guests are expected. Costs range from $500 for an individual ticket to $10,000 for 10 VIP seats, according to the Glass House website.