During the Second World War, Cambridge, like most of England, was under threat of aerial bombardment. The first daylight raids over the country took place in June 1940, and they continued throughout the remainder of the war, killing some 40,000 civilians. Though Cambridge itself was not badly hit, the city experienced 424 air raid alerts during which high-explosive bombs, oil bombs, and other incendiaries were dropped, killing 29 people. Some of the city’s residents may have hidden in a concrete air raid shelter built under the green of Jesus College in 1939. Its outlines are an unexpected reminder of the war only recently made visible.

The raised earthwork motte, or mound, of Castell Llwyn Gwinau, a medieval fortification that sits atop an isolated hill in western Wales, is about five feet high and some 100 feet in diameter. This remote spot is not obviously strategic, and it is possible the tenant of a nearby farmstead built the castle simply to signal his position as a knight. Although the location of the castle was known, the drought made its layout clear. Brown sections at its summit likely mark the remains of a stone wall, and a green ring indicates its ditch. The Royal Commission on the Ancient and Historical Monuments of Wales discovered at least 100 sites during the heat wave. “So much new archaeology is showing, it is incredible,” says Toby Driver, the commission’s senior aerial investigator. “The summer’s urgent work in the air will now lead to months of research in the office in the winter months to map and record all the sites which have been seen and to reveal their true significance.”

Canovium was one of a network of wooden forts that housed tens of thousands of troops during the Roman invasion of Wales in the first century A.D. Around A.D. 120, when many of these soldiers were shipped north to work on Hadrian’s Wall, Canovium was among the forts in Wales made permanent and rebuilt in stone. This past summer, evidence of these stone walls appeared, with just the northeast corner obscured by a still-active medieval parish church.

Based on previous excavations and historical sources, says archaeologist Peter Guest of Cardiff University, the fort is known to have been home to an auxiliary unit. Its 500 soldiers were drawn, at least initially, from recently conquered peoples—most likely Batavians, Gauls, or Thracians. “The fort was occupied for 200 years or more,” says Guest. “It wouldn’t be surprising then if a number of the recruits that lived there grew up just outside the fortress. They were the sons of existing soldiers and the grandsons of soldiers before them.”