The Howell house, 110 West Jefferson St., built in the 1850s, was the home of William Dean Howells (1837-1920), known as the "Dean of American letters" and "father of American realism". Howells' father, William Cooper Howells, and later his brother, Joseph Alexander Howells, both served as the editor of the Ashtabula County Sentinel, the leading liberal newspaper in the county. William Dean Howells was a friend and cohort of Samuel Clemens (aka Mark Twain). In addition to his most famous novel, The Rise of Silas Lapham, and his many other works of literature, Howell was also the editor of the Boston-based Atlantic Monthly. His family is buried in Oakdale Cemetery. The home was also once owned by Joshua Giddings.

Camp Giddings, northwest corner of West Walnut and North Elm Streets, was located on the site of the present Ashtabula County Fairgrounds. Ohio had more volunteers than any other state in the Union. This camp was the home site of the 29th Ohio Volunteer Infantry. On December 25, 1861 1,532 men marched from here to the train station in Ashtabula, where they boarded a train for Camp Chase in Columbus. Among the many engagements the 29th OVI fought in were the battles of Lookout Mountain TN, Chancellorsville VA, Gettysburg PA, and Sherman's March to the Sea. Of their 1,532 men, they suffered 540 casualties. They were mustered out of service in July 1865.

Moved here to Giddings Park, East Jefferson St. in 2018, it was originally located on the east side of N. Chestnut St., where the McDonalds restaurant is currently located. Joshua Giddings was considered to be a Radical Republican. He not only advocated for the abolition of slavery, but for voting rights for African-Americans and women as well! Giddings was responsible for writing several parts of the original platform of the newly formed Republican Party in the 1850s in this very office.

A short distance to the west of this office is the stone that marks the location of the so-called McKinley Elm tree, now lost to time and disease. Future president William McKinley gave a speech under that elm tree in 1892.

In 1876, the cornerstone was laid for the Trinity Episcopal Church. It is a fine representation of the American Gothic Revival style of architecture. After the building ceased operations as a church, it was purchased by the Henderson Memorial Library. In December of 2005, a group of concerned citizens, learning that the building might be moved, altered or destroyed, formed the Jefferson Historical Society and purchased the Trinity Church Building. Through special arrangements with the library, the building was purchased interest-free for $100,000 to be paid back over ten years. The name "Trinity Church Building" was chosen for the home of the Jefferson Historical Society.

The First Congregational Church, 41 East Jefferson St., was founded in 1831, and the brick building was constructed in 1835. Long known for their support of social justice issues, their members have fought for human rights issues from the abolition of slavery to suffrage for women to the enfranchisement of southern African-Americans in the 1960s. Betsey Mix Cowles held a meeting for women's rights here in 1844, four years before the Seneca Falls Convention! And famous abolitionist John Brown preached here in 1859.