The garbha griha or sanctum santorum of the Ram Temple in Ayodhya is expected to be ready and opened to public by the end of 2023, a source familiar with the matters of the Ram Temple trust said. On the occassion of one year of the Bhoomi Pujan (foundation-laying ceremony) of the temple by Prime Minister Narendra Modi, the person said while the temple is likely to have three floors and possibly a Ram Darbar on the first floor, an astronomical study is being done to design a structure that could facilitate the rays of sunshine to fall on deity on the Ram Navami through a window. The temple trust believes the mandir could attract up to ten lakh devotees during festivals.The entire temple complex is expected to be completed by 2025 and is expected to cost around Rs 1,000 cr, sources said. Donations up to Rs 3,000 crore have already been received by the Ram temple, say sources.The temple complex is expected to spread over 110 acres, much larger than the original 67 acres, as the temple trust has acquired more land in the vicinity of the existing complex, the source said. Government sources also told ET that the priority of the trust, which has roped in L&T, TCS and experts from the field of science and technology, was to ensure the stability of both the structure and the soil. The trust, which wants to avoid using steel can last only for a 100 years, plans to use stones to build pillars and copper for joints. It has formed a committee of experts from different IITs to look at soil strength and examine global models. To come up with a safe design for the pillars, members from IIT Delhi, IIT Mumbai, IIT Roorkee, National Building Research Institute (NBRI), Tata Consultancy and Larsen & Toubro will work together, the source said.