With today’s modern expansion of Madrid, The Plaza de Colon joining Chamberi and Salamanca districts and right next to Centro and Retiro districts is what I consider to be the modern day km. 0 of the city (central starting point if you will).
The singularities of this area are plenty, not only will you find the monument dedicated to Christopher Columbus overviewing the main street of the Castellana, but adjacent to the Serrano Street you have three huge concrete blocks composing a Monument in honor of the discovery of America.
Each block is centered on different aspects of their time, and you will find engravings of art and people’s names that were fundamental to the fulfillment of the initial expedition to America. It’s an up close and personal monument and you can actually walk around and between it.
I love to stroll through this place and feel the amplitude this plaza has to offer, and with one full turn of 360º you get a great perception of today’s Modern Madrid.