A volcanic plug, also called a volcanic neck, is a volcanic landform created when magma hardens within a vent on an active volcano. A natural monolith is a mountain or large rock formation consisting of a single massive stone. Both types of these geological structures are similar in that they are often steeply rising above the surrounding terrain. The unusual appearance and the buildings which are often located on these structures, amaze visitors and attract them to come back again.
H/t to Bosco