Older masonry chimneys are also dangerous if they have substantial vertical extension above the roof.

The farther one progresses, the longer is the necessary vertical extension.

The foul pole is a vertical extension of the foul line.

The guideway was roughly the size and shape of a pedestrian sidewalk, with short vertical extension on either side to form a U-shape.

Power was provided via a third rail system attached to the top of the right vertical extension (as seen in the direction of travel).

It is the museum with the biggest vertical extension of the world.

The two vertical external extensions allow preservation of useful interior space at the upper levels.

The poles are a vertical extension of the foul lines.

In 2001, a vertical extension to the building was completed.

During the 12th century, several additions followed, in particular the creation of the main tower as a vertical extension of the existing keep.