While everyone is familiar with the Taj Mahal in Agra, it is only the tip of the iceberg when it comes to the many historical structures, buildings, and landmarks all over the country. The structures and buildings are the remnants of the rich and storied history of the country, both before and after India's independence in 1947. These structures, which range from stunning temples to magnificent palaces and mausoleums, are an important part of India's culture, heritage, and identity and while it's important to preserve these structures, it's also important to preserve the history of India and it's influence on the rest of the world. Many of these structures are also part of UNESCO's World Heritage site, which has helped preserve them for the future.

Humayun's Tomb is especially significant because its architecture was later used as the blueprint for the Taj Mahal - one of the Seven Wonders of the World. Mirak Mirza Ghiyas from Persia was commissioned to build the tomb in 1569, just after the death of the Mughal emperor Humayun in 1556. The tomb is built on a 25-acre plot that has a four-sided garden, which is then divided into 36 smaller squares. Sadly, during the partition of India and Pakistan, Humayun's Tomb was used as a refugee camp for a few years and sustained quite a bit of damage as a result.

Qutub Minar, the tower of Quwwat-ul-Islam mosque, was built by the founder of the Mamluk dynasty, Qutb-ud-Din. His son-in-law Iltutmish added a fourth story and embossed it with stones. It was later damaged by lightning and King Firoz Shah Tughlaq commissioned repairs and added a fifth story. The first three floors are made of red sandstone while the two upper floors are made of marble and sandstone. The intricate carvings from Quran on each floor will leave you amazed. 

The Red Fort is a stunning example of traditional Mughal architecture that has been expertly blended with Persian and European influences. The fort was originally built with lime plaster, but as it started to peel, the British painted it red. The Pearl Mosque was built near Emperor Aurangzeb's chamber. The Red Fort campus features a fusion of Persian, European, and Indian architectural styles.

The Purana Qila is an excellent example of architectural harmony between Muslim and Hindu styles. Sher Shah built the Qila and surrounded it with a city. Humayun, Talaqi, and Bara Darwaza are the three gates of the fort. Sandstone was used to build each double-tier rampart. The gates were surrounded by a moat through which the Yamuna used to flow once upon a time.

Sher Mandal is a historic building situated inside Purana Qila. It was built by the Mughal emperor Humayun as an observatory, library, and pleasure house. Sher Mandal is octagonal in structure and consists of two stories. The floors are made of marble and the building is constructed of local red sandstone. Both floors are crowned with a verandah that runs around the perimeter.

The legendary poet Mirza Ghalib's haveli is one of Delhi's most remarkable structures that is often overlooked. Ghalib's house has sandstone floors and Lakhori bricks, with arched corridors enclosing a courtyard on three sides. The structure represents the architectural style at the end of the Mughal era. Unfortunately, only a portion of the haveli was acquired and restored by the government; the remainder has fallen into disrepair.

After relocating his capital from Agra to Shahjahanabad, Shah Jahan commissioned the construction of the Jama Masjid (Old Delhi). It took about six years to build in red sandstone and marble. The interiors are reminiscent of Agra's Jama Masjid. The courtyard floor is sandstone, with marble strips indicating prayer positions to the average citizen.

The Tughlaqabad Fort was built by Ghiyas-ud-din Tughlaq, the founder of the Tughlaq dynasty in Delhi, to keep enemies out and to serve as the king's capital. Its double-tiered bastions and massive ramparts are architectural marvels. Inside the fort were grand mosques, an audience hall, and beautiful palaces in an Indo-Islamic style.

Mirza Muqim Abul Mansur Khan, also known as Safdar Jung, is buried at the Safdarjung Tomb. It was made of sandstone and marble, and after his death, his son Nawab Shujaud Daula begged the Mughal emperor to allow him to build a tomb for his father in Delhi. The tomb was designed by an Abyssinian architect to look like Humayun's Tomb.