Tamil Nadu (; Tamil: [ˈtamiɻ ˈnaːɽɯ] (listen), abbr. TN) is a state in southern India. It is the tenth largest Indian state by area and the sixth largest by population. Its capital and largest city is Chennai. Tamil Nadu is the home of the Tamil people, whose Tamil language—one of the longest surviving classical languages in the world—is widely spoken in the state and serves as its official language. The state lies in the southernmost part of the Indian peninsula, and is bordered by the Indian union territory of Puducherry and the states of Kerala, Karnataka, and Andhra Pradesh, as well as an international maritime border with Sri Lanka. It is bounded by the Western Ghats in the west, the Eastern Ghats in the north, the Bay of Bengal in the east, the Gulf of Mannar and Palk Strait to the south-east, and the Indian Ocean in the south. The at-large Tamilakam region that has been inhabited by Tamils was under several regimes, such as the Sangam era rulers of the Chera, Chola, and Pandya clans, the Pallava dynasty, and the later Vijayanagara Empire, all of which shaped the state's cuisine, culture, and architecture. After the fall of the Kingdom of Mysore, the British colonised the region and administered it as part of the Madras Presidency, headquartered at the city of Madras, now known as Chennai. After India's Independence in 1947, the Madras State came into existence, whose borders were linguistically redrawn by the States Reorganisation Act, 1956, losing territory to Kerala, Karnataka and Andhra Pradesh. The state was renamed as Tamil Nadu in 1969. It is home to a number of historic buildings, multi-religious pilgrimage sites, hill stations and three World Heritage Sites.The economy of Tamil Nadu is the second-largest in India, with a gross state domestic product (GSDP) of ₹24.85 lakh crore (US$310 billion) and has the country's 11th-highest GSDP per capita of ₹225,106 (US$2,800). It ranks 11th among all Indian states in human development index. Tamil Nadu is the most urbanised state in India, and one of the most industrialised states; the manufacturing sector accounts for more than one-third of the state's GDP. Its tourism industry is the largest among the Indian states. The Tamil film industry plays an influential role in the state's popular culture.

Dehradun () is the capital and the most populous city of the Indian state of Uttarakhand. It is the administrative headquarters of the eponymous district and is governed by the Dehradun Municipal Corporation, with the Uttarakhand Legislative Assembly holding its winter sessions in the city as its winter capital. Part of the Garhwal region, and housing the headquarters of its Divisional Commissioner. Dehradun is one of the "Counter Magnets" of the National Capital Region (NCR) being developed as an alternative center of growth to help ease the migration and population explosion in the Delhi metropolitan area and to establish a smart city in the Himalayas. It is the third largest city in the Himalayas after Kathmandu and Srinagar. Dehradun is located in the Doon Valley on the foothills of the Himalayas nestled between Song river, a tributary of Ganga on the east and the Asan river, a tributary of Yamuna on the west. The city is noted for its picturesque landscape and slightly milder climate and provides a gateway to the surrounding region. Dehradun is a notable academic and research hub and is home to the Indian Military Academy, Forest Research Institute, Indira Gandhi National Forest Academy, The Doon School, Welham Boys School, Welham Girls School, Brightlands School, Rashtriya Indian Military College, Uttarakhand Ayurveda University, Wadia Institute of Himalayan Geology and the Indian Institute of Remote Sensing. It is the headquarters of the Surveyor-General of India. According to the combined survey based on health, infrastructure, economy, education, and crime, conducted by Dainik Jagran and KPMG, Dehradun is one of India's safest cities. Dehradun is also known for its Basmati rice and bakery products. Also known as the 'Abode of Drona', Dehradun has been an important center for Garhwal rulers and was captured by the British. For its strategic value, in addition to the location of its principal service academy, the Indian Armed Forces maintain a considerable presence in Dehradun, at the Garhi Cantonment and Naval Station. The Uttarakhand Police is the primary law enforcement agency in the city. It is well connected and in proximity to Himalayan tourist destinations such as Mussoorie, Dhanaulti, Chakrata, New Tehri, Uttarkashi, Harsil, Chopta-Tungnath, Auli, and famous summer and winter hiking destinations like the Valley of Flowers at Dodital, Dayara Bugyal, Kedarkantha, Har Ki Dun and Hemkunt Sahib for camping and Himalayan panoramic views. The Hindu holy cities of Haridwar and Rishikesh, along with the Himalayan pilgrimage circuit of Chota Char Dham, viz. Yamunotri, Gangotri, Kedarnath and Badrinath, are also primarily accessed via Dehradun, the closest major city.