Jubilee is what it is called. Jubilee meaning is:

A jubilee is a particular anniversary of an event, usually denoting the 25th, 40th, 50th, 60th, or 70th anniversary. Of biblical origins, the term is often now used to denote the celebrations associated with the reign of a monarch after a milestone number of years have passed.

An obelisk is a stone building particularly in a square or rectangle formation which ends with a pyramid shape on top.

is a tall, four-sided, narrow tapering monument which ends in a pyramid-like shape or pyramidion at the top.