A modern call to the classical form of monument the tetrapylon—Greek for four gates.
Compare with the Roman construction at Palmyra, in Syria.
It serves no function, but marks the possible significance of a point, and announces intersection and can stand at one, as it did in Palmyra.
Remains of the Palmyra tetrapylon in 2016. . .
before it was destroyed by the Islamic State in 2017.
It can stand in a public square, or it can be placed in a park, in an open field, as I have done, inviting the concept of intersection. Visitors can make it a destination and pass through or rest or gather on the platforms at the corners.
At different viewing angles it shifts in varying degrees of closure and separation
and different patterns of the columns.
Imaginary depiction of the Tetrapylon of Palmyra, ca. 1799.
First photo and etching via Wikipedia.