Monticello's first resident was George Haworth. Haworth came to the area in 1822 to serve as a U.S. liaison agent to local Native American tribes. Haworth did not remain, but in 1829, James A. Piatt purchased Haworth's small log cabin. Soon more settlers arrived.
In 1837, residents decided to form a new town which was christened Monticello – after the home of Thomas Jefferson. Monticello officially became a town on July 1, 1837. Townsfolk held a celebration on July 4.Monticello continued to grow as the population increased over the next decade.
A new county was established on Jan 27 1841: Piatt County - named in honor the first permanent settler, James A. Piatt. As it was the only town in the area at that time, Monticello was named the county seat. The county began legal functions on April 5, 1841 in the "Old Fort." In 1843, the first courthouse was built on land donated by William H. Piatt.
Monticello's star resident arrived in 1885. Dr. William B. Caldwell came to practice medicine in Monticello but his homemade mixture of senna and pepsin brought Monticello to a level of national prominence. The Pepsin Syrup Company was founded in 1893, and became the leading employer in the city for decades until its closure in 1985. （History from 1985 - now）
- Abe Lincoln - Monticello was part of the 8th Judicial Circuit that Lincoln served in from 1847-1859. The Monticello Railway Museum, announced the formal dedication of the Looking for Lincoln wayside storyboard sign in conjunction with their 2009 Railway Days event. The Looking for Lincoln sign tells the story of how Abraham Lincoln promoted and contributed to the expansion of railroads in Piatt County, Illinois. This sign dedication is very unique, symbolic and illustrates Abraham Lincoln's contributions, vision and promotion of building and expanding not only the network of railroads within Illinois, but in linking the west and east coast of the United States with the building of the Transcontinental Railroad, which was completed on May 10, 1869.
- Allerton Park - The Robert Allerton Park is a 1,517 acre (6.0 km²) park, nature center, and conference center located near Monticello, Illinois on the upper Sangamon River. It has been described as "a vast prairie turned into a personal fantasy land of neoclassical statues, Far Eastern art, and huge European-style gardens surrounding an English Tudor-style. It has been given National Natural Landmark and National Register of Historic Places designations.
- 1 Monticello Railway Museum, 992 Iron Horse Place, ☏ . Offers train rides on weekends and holidays from May through October, and on special occasions. They also collect, preserve and exhibit materials and artifacts like rail cars and other equipment from the history of railroads. Free on Father and Mothers day for moms and dads respectively, 30 minute course: $100,.
- Monticello Sages - Homecoming festivities – Every year, Monticello High school has a parade celebrating their homecoming festivities. Friday afternoon, the homecoming parade begins from the high school promptly at noon. Friday evening's festivities will begin in the high school Media Center with the Hall of Fame. At 6:45PM, the festivities continue as everyone proceeds to the football field. For more information call the high school office at +1 217 762-8511 ext. 1210.
- Millionaire Row & Historical Homes - The founders of the Pepsin Syrup , a notable patent medicine company, contributed to the spawn of construction of mansions on North State Street that became known as "Millionaire's Row. South Charter Street: The South Charter Street Historic District represents some of the city's first growth outside of the Original Town plat and was basically the first of the city's premier residential addresses. In contrast to the North State Street Historic District, the architecture of the South Charter Street Historic District is more varied and is generally less high style.
- 1st Friday on the Square - On Fridays, from 5pm - 9pm it's Shopping, Dining and a Movie in beautiful downtown Monticello. On the 1st Friday of each month, Monticello invites you to visit the restaurants, cafes, galleries and shops while enjoying live music, children's activities and more.
- Barn Tour - Every year, Piatt County celebrates its rich agricultural history along a 35-mile historic and scenic route through Goose Creek Township. Guests can visit 20 barns, explore Centennial farms, discover restored pioneer cemeteries and other historic sites including part of a trail traveled by Abraham Lincoln while he practiced law as a circuit-rider throughout Central Illinois.
- Christmas in July - Come join the merchants of Courthouse Square for an early look at Christmas. Activities are set for children and adults alike to bring a breath of fresh air to the middle of summer.
- Chocolate Fantasy - The Annual Chocolate Fantasy, held just days before Valentine's Day, will be filled with great ideas for all of the special people in your lives. Whether you are buying for your sweetie, mom, dad, teacher, or best friend you will be able to find something for everyone on your list
- Farmer’s Market - On State and Livingston Streets join Monticello’s Main Street Farmer's Market featuring many of your favorite vendors selling seasonal fruits, vegetables, plants, flowers, breads, and more.
- Garden Walk, ☏ , ✉ email@example.com. Annual Monticello Chamber Garden Walk. For tickets, please contact the Chamber Office.
- May Market - You know it's Spring when the Monticello Main Street May Home & Garden Market is around the corner! The special day is set for Saturday, May 1, 2010. There are plants, herbs, garden containers and garden accessories.
- Monticello Car show - The Monticello Car, Truck and Motorcycle show takes place at the Courthouse Square in downtown Monticello. Judging starts at noon for Best of Show, Best Truck, Best Motorcycle, and distance travelled, and Club participation.
- Monticello Celebration - That's Main Street’s Annual Monticello Celebration is filled with a great variety of Art and Craft vendors throughout the downtown square. Don’t miss the very popular Pet Parade and Contest or Kid’s Activity Area including a Bounce House, Giant Slide, Obstacle Course and Giant Choo-choo.
- The Monticello Country Club - A semi-private golf course, inviting both memberships and public play has majestic oaks, meandering creeks and ponds providing an excellent setting for this challenging, but enjoyable 18 hole championship course.
- Monticello Main Street Ornaments - Monticello Main Street is proud to offer a collection of holiday limited edition ornaments, all depicting scenes from historic Monticello. They are hand sculpted in a material called “bonded marble” and then hand-painted in a holiday scene.. These ornaments will be offered for sale at most of the restaurants and shops in Courthouse Square in downtown Monticello. You may order your ornament at +1 217 762-9318 or email firstname.lastname@example.org.
- WackyNackies Gifts & Cafe, ☏ . Featuring Gourmet Foods, Handbags, Home Décor, Jewelry & Accessories, Children’s Gifts, and Bath & Body.
- Boka Shoppe, toll-free: . Family owned and operated florist.
- Celebrations (Wedding Invitations). Offers a line of personalized accessories and invitations for wedding receptions. +1 217 762-325
- Casey's Carry Out Pizza, 301 S Market St, ☏ .
- Filippo's Pizza & Italian Food, 200 S Market St, ☏ .
- Monical's Pizza, 707 W Bridge St, ☏ .
- Corner Tavern, 219 W Washington St, ☏ .
- Brown Bag Deli Restaurant, 212 w Washington st, ☏ .
- Jittrs Restaurant, 106 South Charter, ☏ .
- Judy's Crossroads Cafe, 915 N Front St, ☏ .
- Monticello Red Wheel, 803 Iron Horse Pl, ☏ .
- Three Ravens, 108 S Charter St, ☏ .
- China Star, 400 W Center St, ☏ .
- Los Toros, 1204 Bear Ln, ☏ .
- Pies By Inge, 212 W Washington St, ☏ .
- The Brown Bag Deli Restaurant, 212 W. Washington, ☏ . In business for 33 years. A traditional deli unique to the city.
- The Corner Tavern, 219 W Washington St, ☏ .
- East End Tavern, 116 E Washington St, ☏ .
- The Main Street Pub of Monticello, 113 West Main Street, ☏ .
- Best Western Hotel, 101 N Market St, ☏ .
- Best Western Monticello Gateway Inn, 805 Bensyl Dr, ☏ .
- Foster Inn, 1414 N Market St, ☏ .
- Monticello Best Western Gateway Inn, 805 Iron Horse Place, ☏ .
- Monticello Chamber of Commerce, PO Box 313, ☏ , toll-free: , ✉ email@example.com.