No surprise that in a state founded in 1776 you’ll find living history wherever you look — no more so, perhaps, than in the buildings and structures that are as much of the landscape as the sandy beaches, sparkling waters, and well-manicured greens of our Connecticut towns. In addition to being historic landmarks — as well as originally inhabited by larger-than-life figures — each of these homes has a story to tell, and has its doors open to you.

Mark Twain may conjure up the image of a happy-go-lucky hometown boy from Missouri seeking out adventures that eventually will be transformed into unforgettable stories. That the actual Mark Twain, born Samuel Langhorne Clemens, lived in a three-story, 25-room Neo-Gothic mansion in Hartford, adds a certain plot twist to his story.

Named as “one of the 10 best historic homes in the world” by National Geographic, the Mark Twain House, built in 1874, offers tours to visitors that — literally — take you inside the daily life of the beloved author. Each tour guide presents a significant figure from Twain’s life at different times (his housemaid, his wife’s maid, his coachman), giving first-person accounts of his private life and work. Better yet, there are only a few rope-lines, so you feel as though you’re in a house, not a museum.

While a guided tour is $20 and lasts about an hour, it’s suggested that you reserve about two hours to view the Ken Burns film, “Mark Twain,” and tour the museum exhibits and grounds.

It may well be that you, or members of your travel party, have read one of the works Twain penned at a desk in the billiard room, including “The Adventures of Tom Sawyer” and “The Adventures of Huckleberry Finn.”

The house, which the literary giant described as “something between a Mississippi steamboat and a cuckoo clock” and Time Magazine termed “Downton Abbey’s American cousin,” is sure to delight.

The Mark Twain House & Museum, 351 Farmington Ave., Hartford, CT 06105. 860-247-0998. www.marktwainhouse.org.

In the category of eccentric homes in Connecticut, it’s fair to say that Gillette Castle is king. William Gillette was a much-admired American actor known for his stage portrayal of Sherlock Holmes, which he performed more than 1,000 times. Starting in 1914, he used the tidy million he amassed to design a 24-room 14,000-square-foot medieval fortress on a 184-acre plot of land in East Haddam that’s now home to Gillette Castle State Park.

The castle features a number of idiosyncratic touches, including its 47 doors, each of which has a unique wooden puzzle lock that Gillette also devised. There’s also a disappearing bar (used extensively during Prohibition) and a set of mirrors that afforded the voyeuristic Gillette a view of the main room of the castle from the master bedroom in order to make the proper grand entrance when guests arrived.

Some of those guests, like friends Albert Einstein, Helen Hayes and Charlie Chaplin, enjoyed rides on the custom-made cars of the 3-mile miniature railway built by train-buff Gillette.

Self-guided castle tours are offered continuously from 10 a.m. until 5 p.m. daily from Memorial Day weekend through Labor Day weekend. Allow about an hour to explore the interior. Staff is available to assist with questions about the castle’s interior and its history.

While the castle is the main attraction, the grounds, which are open year-round, are equally impressive, providing scenic Connecticut River views and opportunities for picnicking and hiking. Check out the Railroad Trail, which meanders through the property along the route once followed by the railway. Or walk through a 500-foot-long rail tunnel drilled into a hill.

From Deep River near Essex, the castle is approachable by a three-minute ferry ride across the Connecticut River, or by car from the castle side. (We recommend the ferry ride.)

Gillette Castle State Park, 67 River Road, East Haddam, CT 06423. 860-526-2336. https://www.ct.gov/deep/cwp/view.asp?a=2716&q=325204&deepNav_GID=1650

Unlike the structures built by Mark Twain and William Gillette, Philip Johnson’s Glass House, situated atop a dramatic hill on a rolling 47-acre estate in New Canaan, is a piece of architecture that’s renowned not for what it includes, but for what it leaves out.

The weekend home Johnson, who died in 2005, designed for himself in 1949 suggests a life pared down to bare essentials. The “architectural equivalent of a brilliantly packed suitcase,” as Architectural Digest put it, the structure includes a bedroom, bathroom, kitchen, and space for dining and entertaining all arranged inside a glass rectangle measuring 32 by 56 feet. While it feels simple and spare, it’s well appointed with everything you need to live comfortably, nothing more or nothing less.

It’s also, according to Johnson, the architect who designed the JFK Memorial in Dallas, the Lipstick Building in New York, and the Nieman Marcus Department Store in San Francisco, a platform for viewing nature. The walls consist solely of 18-foot-wide, floor-to-ceiling plate glass sheets that have the lush landscape seamlessly flowing through the house.

Tours of the Glass House are available from May to November. There are self-guided, private, and group tours, as well as a three-hour in-depth tour, that includes most of the buildings on the property. Advance reservations are required.

The Glass House, 199 Elm St, New Canaan, CT 06840. www.theglasshouse.org.

Lisa Reisman is a freelance writer for the Hearst Connecticut Media Group.

Connecticut Media Group