Which famous monument in India was designated as a UNESCO World Heritage Site in 1983 and is renowned for its intricate marble carvings, symmetrical design, and harmonious blend of Islamic and Persian architectural styles?

The Taj Mahal, located in Agra, Uttar Pradesh, is the correct answer. It was designated as a UNESCO World Heritage Site in 1983. The Taj Mahal is a mausoleum built by the Mughal Emperor Shah Jahan in memory of his wife Mumtaz Mahal. It is celebrated for its exquisite white marble construction, intricate inlay work, and its harmonious blend of Islamic, Persian, and Indian architectural influences. The Taj Mahal is considered a masterpiece of Mughal architecture and a symbol of eternal love.