According to both indigenous American and European accounts and documents, American civilizations at the time of European encounter had achieved many accomplishments. For instance, the Aztecs built one of the largest cities in the world, Tenochtitlan, the ancient site of Mexico City, with an estimated population of 200,000. American civilizations also displayed impressive accomplishments in astronomy and mathematics. The domestication of maize or corn required thousands of years of selective breeding.
What had the Aztec civilization constructed?
one of the largest cities in the world

From the German point of view, March 1941 saw an improvement. The Luftwaffe flew 4,000 sorties that month, including 12 major and three heavy attacks. The electronic war intensified but the Luftwaffe flew major inland missions only on moonlit nights. Ports were easier to find and made better targets. To confuse the British, radio silence was observed until the bombs fell. X- and Y-Gerät beams were placed over false targets and switched only at the last minute. Rapid frequency changes were introduced for X-Gerät, whose wider band of frequencies and greater tactical flexibility ensured it remained effective at a time when British selective jamming was degrading the effectiveness of Y-Gerät.
Why was the X-Gerat frequencies used more?
British selective jamming was degrading the effectiveness of Y-Gerät

Bern lies on the Swiss plateau in the Canton of Bern, slightly west of the centre of Switzerland and 20 km (12 mi) north of the Bernese Alps. The countryside around Bern was formed by glaciers during the most recent Ice Age. The two mountains closest to Bern are Gurten with a height of 864 m (2,835 ft) and Bantiger with a height of 947 m (3,107 ft). The site of the old observatory in Bern is the point of origin of the CH1903 coordinate system at 46°57′08.66″N 7°26′22.50″E﻿ / ﻿46.9524056°N 7.4395833°E﻿ / 46.9524056; 7.4395833.
Where is Bern located?
the Swiss plateau in the Canton of Bern