Park your car in the garage on the St. Louis Gateway Arch grounds. Walk along the river south about two blocks to the steps leading up to the Arch. Notice the large granite blocks on the levee between the street and the water (unless the river is in flood stage). From the Arch steps you can get your bearings. Look east across the river to Illinois. Look south to the highway bridge next to the railroad bridge. Look west through the Arch to the buildings of downtown St. Louis. Notice the roof of the building that looks like an Egyptian stepped pyramid, the federal court building. The domed building is the Old Courthouse. Look north. The Eads Bridge you see across the river is the oldest bridge.
Touch the Arch. The triangular sections form the tallest of our national monuments. The Arch is a free-standing monument that is at the top of a long flight of concrete steps that lead up from the riverfront. If you face the Arch with your back to the river you will be looking west. The Arch has two bases. If you are looking west, one triangular base is to your left, facing south and the other foot is to your right, facing north. Descending the stairs at whichever base you prefer to enter the Museum of Westward Expansion, the guest shop, and the ride to the top. It is well worth the wait to go through the airport-like security metal detectors. Inside you can watch a movie of the construction of the Arch. Visit the museum and see a sod house, various tools and weapons, Native American memoribilia, and a wonderful photographic exhibit of the Lewis and Clark expedition. Buy a ticket to ride up the Arch to the observation deck at the top. In clear weather you can literally see for miles out of the little windows.
Walk west and south away from the river to the stone church which was built in 1830. This is commonly known as the Old Cathedral. It is one of St. Louis' two Catholic Basilicas. Inside the simple sanctuary there are interesting statues and paintings depicting the life of the patron saint of St. Louis, French King Louis IX. In the basement of the church there is a museum of Catholic treasures including some reliquaries and a bell which was baptised to please the Native Americans in the early days of the city.
Leave the church and cross over the depressed section of the interstate to Market Street. Go up the hill for about a block to the domed building that was framed by the Arch when you looked west from there. This is the Old Capital. It is also a museum with interesting paintings and artifacts. The south side of the Old Capital was the where St. Louisans bought and sold African American slaves before the Civil War and the building itself was where the Dred Scott case was first argued.
Go back through the Arch grounds and walk north along the river. If you have time you can take a river boat cruise on the Becky Thatcher boat. This goes north to Alton, Illinois through the lock on a two hour ride. You can walk across the Eads Bridge to Illinois and back. Sometimes the bridge is host to local restaurants. Visit the casino. Climb up to Laclede's Landing. This raised area has the original coblestone streets. Here there are pubs, restaurants, and interesting little shops. Laclede's Landing has a highly developed night life. When you are ready to go home, your car is just a block away in the garage.