airport control control tower former standby tower tower views unused visibilty air traffic control airline airplane architecture atc aviation berlin command flight fly holidays plane radar tower signal tracking traffic air-traffic-control aircraft architectural communications control-tower directions directives flying height high safety tower-signals tower-views Australia buildings harbour Melbourne sea shipping skies towers CO colorado Denver dia bridge flow forest Great Britain green hills lake management reservoir spring station stone wales water welsh beacon black building castle Chaderton Castle England english Hampshire Historic site historical landmark lighthouse lookout observation tower Portsmouth Southsea Castle wall white binnensee blauer Himmel erholung freizeit geierswalde Geierswalder See house lausitz lausitzer seenland Leuchtturm see sommer sport urlaub wasser wassersport clouds communication hill mast microwave network radio transmitter