During the DC Solar Tour this weekend, more than 70 eco-friendly homes open their doors to the public. Spread out across the area—from Baltimore and Frederick to Lorton and Manassas—the tour sites use all sorts of cutting-edge  green technology. You’ll see tankless water heaters, low-water consumption toilets, green roofs, and more. 
October 3 and 4 from 11 AM to 5 PM. Admission is free with a copy of the brochure, available here.

In its 54th year, the Potomac Country House Tour showcases four homes in the ritzy Montgomery County suburb. Highlights of this year’s tour include a French Country Manor and a replica of Chownings Tavern, a 230-year old landmark in Williamsburg.
October 3 and 4 from Noon to 5 PM. Tickets are $25, $20 in advance.

Fourteen Eastern Shore designers have redone the rectory of the Church of Holy Trinity in Oxford, Virginia. Called the Country Rectory Showhouse, the newly decorated spaces are on view through October 4. Suzanne Hanks of S. Hanks Interior Design has designed the master bedroom in a green and creme color scheme that matches the foliage outside the bedroom’s windows. Designer Maggie Sarsaty painted animals along the walls of the foyer and staircase.
Friday and Saturday from 10 AM to 4 PM; Sunday from Noon to 4 PM. Admission is $20 at the door. For more information, call 410-226-5400.   

Five houses open their doors during the 8th annual Reston Home Tour. Called “New Visions,” the tour features residences that have been gutted and remodeled in the neighborhoods of Heron House, Waterview Cluster, South Lakes, and Northpoint. Tour-goers can also stop by the Fairfax Hunt Club for a cooking demonstration and tasting by chef David Winter of J.R. Stockyards Inn in Tysons Corner.
October 17 from 10 AM to 5 PM. Tickets are $30, $25 in advance.  

This year’s Historic Ellicott City Decorator Show House takes over Walnut Grove, a stone estate that dates to the 1780s. Twenty interior designers— such as MK Designs, Simply Put Interiors, Chelsea Interiors, and Carroll Fey Interiors—have redone the mansion.  
Open through October 18. Hours are Tuesday, Wednesday, Friday and Saturday from 10 AM to 4 PM, Thursday from 10 AM to 8 PM, and Sunday from 12 PM to 5 PM. Tickets are $20, $15 in advance.

During the Dupont Circle House Tour, visitors have a chance to explore 14 residential homes and historic buildings. Tour highlights include a house with a floating staircase, another with a secret garden, and the John Ross Elementary  School, which was built in 1888. You’ll also get to peak inside the “former White House” at 15 Dupont Circle, where Calvin Coolidge lived in 1927 while the White House was undergoing renovations.
October 18 from Noon to 5 PM. Tickets are $30, $25 in advance.
 
If you’re looking for some face time with interior designers, the Washington Design Center hosts a free meet-and-greet with the pros who worked on its Fall 2009 Design House. The theme for this year’s house is “Potomac Fever”—eight rooms have been designed to represent different historic districts in Washington including Wesley Heights and Massachusetts Avenue. 
The meet-and-greet is October 17 from 11 AM to 1 PM. The design house is open Monday through Friday from 9AM to 5 PM and Saturday from 10 AM to 3 PM through December 12. Admission is free.