Talatal Ghar

The Talatal Ghar ( ) is located in Rangpur, 4 km from present-day Sivasagar, Assam. It is one of the grandest examples of Tai Ahom architecture. The Talatal Ghar is also the largest of all Tai Ahom monuments.
Visitors nowadays are only allowed to scout through the ground floor, the first floor, and what remains of the 2nd and 3rd floors of the Talatal Ghar. The floors of the Talatal Ghar below the ground have been sealed off, as visitors tended to get lost within its mazy structure and were never heard of thereafter.
History.
Swargadeo Rudra Singha shifted the capital of the Ahom Kingdom from
Garhgaon to 
Rangpur in AD 1702-03. For about a century thereafter, Rangpur remained the capital. It is located in the western part of Sivasagar. The earliest constructions were commissioned by Swargadeo Rudra Singha in AD 1698. Rangpur was the capital of the Ahom Kingdom and served as its military-station.
Architecture.
The Talatal Ghar is a place which was initially built as an army base. It houses two secret tunnels, and three floors below ground level which were used as exit routes during the Ahom wars (and which give the structure its name).
The Rangpur Palace is a seven-storied structure (1751-1769 CE).
However the first Ground Penetrating Survey (GPR) in the northeast, undertaken at two Ahom monuments in Sivasagar district in early Apr 2015, has not revealed the existence of any secret tunnel. The survey was carried out by IIT-Kanpur, in collaboration with the Guwahati circle of the Archaeological Survey of India (ASI), over a period of five days at Talatal Ghar and Ahom Royal Palace (Kareng Ghar), both in Sivasagar district.
Visitors nowadays can only view the ground floor, the first floor, and what remains of the 2nd and 3rd floors .The floors of the Talatal Ghar below ground have been sealed off, and most of the wooden parts of the palace have disappeared over time.
The Rangpur Palace was once surrounded by a brick fortification and an earthen fort (Garh) with dikes filled with water. There is a Gola Ghar (gunpowder and ammunition store) near the palace.