23 meters
The highest point is Maromokotro, in the Tsaratanana Massif region in the north of the island, at 2,876 metres (9,436 ft).
I would consider the roofline the highest point, or the "ridge".
A big fat cow
highest point-mount Everest height-8848m.
The highest point in Papua New Guinea is Mount Wilhelm, with a height of 4,510m.
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The highest point is Mount Cheaha, at a height of 2,413 ft (735 m).
The Longfellow Bridge has a height of about 70 feet (21 meters) from the surface of the water to the apex of the arch at its highest point.
The highest point in Colorado is Mount Elbert (4401 metres) and the highest point in the Netherlands is de Vaalserberg (321 metres) so the difference is 4080 metres (approximately 13385.8 feet).
Madagascar's highest peaks arise from three prominent highland massifs: Maromokotro 9,436 ft (2,876 m) on the Tsaratanana Massif is the island's highest point,followed by Boby Peak 2,658 m (8,720 ft) on the Andringitra Massif and Tsiafajavona 2,643 m (8,671 ft) on the Ankaratra Massif.The lowest points in Madagascar are at sea level, the Indian Ocean 0 m.
If the base of the elevation is at a distance d from the observer, then the highest point is at a height = d*tan(angle of elevation)
Contour lines are spaced at a regular height above sea level - every 50 metres, for example. The highest point of a hill may be just above the highest contour line. Therefore a spot or summit height symbol may be used to mark the highest point on the map.