If you only have 2-3 hours to spend in Newark-on-Trent, here are some suggestions:
Visit the ruins of Newark Castle, a 12th-century royal castle that played a significant role during the English Civil War. It will take you about 1-2 hours to explore the castle and its surroundings.
Stroll around Newark Market Place, where you can find a variety of stalls selling fruits, vegetables, flowers, and other products. The market is open every day except Sundays and takes about 30 minutes to an hour to explore.
Discover the fascinating history of the English Civil War at The National Civil War Centre. The museum has interactive exhibitions and displays that will take you through the events that shaped the course of British history. Plan to spend about 1-2 hours here.
Explore the Newark Parish Church of St Mary Magdalene, a magnificent 12th-century church with impressive stained-glass windows. You can take a guided tour or just admire the architecture and interior decoration. It will take you about 30 minutes to an hour to visit.
These are just a few suggestions, but there are many other things to see and do in Newark-on-Trent. Depending on your interests, you can also visit museums, parks, and galleries or walk along the river or canal. Have fun exploring!