What is the top stone of a catenary arch?

What river was the Great Sphinx flourished in? Where does river soar end? How tall is rockafella center ny? Where is the John Scott Garbry Museum in Piqua Ohio located? What was the width of the Strait of Gibraltar 1 million years ago? What is a city at the mouth of the river mersey? What is the population a Mount Everest? How do you think the increase in traffic affected the cities along this route? What is at the American Museum of Natural History in New York City? What are some of the geologic features in the dead sea? What is jhumming? Why is a desert cooler at night than moist places? What seas surround Sardinia? What was the purpose of building the Augusta canal? What did John Quincy Adams do to help end slavery? What major city would you find along the Thames River? Where is the Lake Wales Museum And Cultural Center in Lake Wales Florida located? Is there a beach in Calais? When people bury themselves at the beach up to there head has the sand ever shifted and people sank into the sand feet underneath the surface and died? When the Empire State Building was constructed there was a mooring mast on the top of the building a long pole-like structure that had a purpose what was its purpose and did it work?