This is a consecrated space of Sri Maa Ambaji Shaktipeeth where Mata Sati’s heart fell off. You can make offerings and go close to the Devi. There is space to sit and meditate. You can go into meditative states here effortlessly.
How to get there
The temple is at walkable distance from Ambaji bus station.
Map: https://goo.gl/maps/QDhoV7Cr89duCRDZ9
About Harsiddhi:
Shri Arasuri Ambaji Mata Temple is the origin of the Supreme Cosmic Power of the Universe. This Temple is one of the 51 (Fifty One) famous ancient Shakti Piths Tirth of Shri Adhya Shakti Devi.
The Great Miracle of this Holy Place is that there is no idol or picture in the Nij Mandir of Shri Arasuri Mata Ambaji, but a simple cave like Gokh in the inner wall, in which A Gold Plated Holy Shakti Visa Shree Yantra, having kurma back convex shape and 51 Bijpatra(Letters) therein, like that of the original Yantras of Nepal and Ujjain Shakti Piths, is ritually installed in such a way it can be visible for devotion, but it was never photographed in past nor in future.
Source:
http://www.ambajitemple.in/page_content.php?cid=22¤t=3