Istanbul Airport is set to become one of the world's top five airports within four years, with the number of passengers predicted to top 100 million. For many, the city that straddles two continents offers a veritable feast of surprises and attractions. Formerly known as Constantinople, even travellers of yesteryear described the city as an assault on the senses.

With a steady influx of new globe-trotters looking to stay over for the 'Istan-Cool' experience while passing through for onward journeys, we give you a heads-up on the places and attractions that will leave a lasting impression long after leaving the city.

Hagi Sophia

6 Gems To Explore In Istanbul - The Wise Traveller - Hagia Sophia

The Hagia Sophia is as much tied to Istanbul's heritage as the Taj Mahal is to India's. The building, which includes Byzantine and Ottoman architecture, was built more than 1,500 years ago, firstly as a Greek Orthodox basilica, but through the ages, it changed emphasis until, in 2020, it was decreed as a mosque.

The unique blend of Christian and Islamic art under the beautiful domes and the majestic aesthetics of its architectural complexities are just jaw-dropping. The building sits atop the historic area of Istanbul, surrounded by the Bosphorus, the Golden Horn and Sea of Marmara.

For those looking to indulge further, a building in Sultanahmet Square has been transformed into a museum that chronicles the changes of the Hagia Sophia since its construction.

Blue Mosque

6 Gems To Explore In Istanbul - The Wise Traveller - Blue Mosque

Otherwise known as the Sultanahmet Camii, it is understandably one of the best attractions that sum up Istanbul. The mosque, which took seven years to build in the early 17th century, is renowned for its six minarets, beautiful exteriors, and the interior's blue Iznik tiles, which give the building its iconic name.

The Blue Mosque offers a glimpse of the culture of the Islamic Ottoman Empire of yesteryear. Commissioned by Sultan Ahmed I and created by Mehmet Ağa, it also features intricate aesthetics such as calligraphy and stained glass windows. It has been a UNESCO World Heritage Site since the mid-1980s.

Topkapi Palace

Sticking close to the former Ottoman ruler, later-day visitors to the Topkapi Palace will enjoy what many humble visitors could not see in the 15th century. With European, Islamic and Ottoman influences, the Palace served as the Ottoman Sultans' residence for 400 years.

Each room within the 700,000 sqm complex is a direct nod to the fabled and wealthy lives of the Sultans. Some of these included the harem quarters for their wives and lovers. Visitors are often awed by the sumptuous environment, designs and artwork. No wonder the UNESCO World Heritage site is one of the most visited in Istanbul.

Grand Bazaar

A visit to Istanbul cannot be contemplated without at least a visit to the Grand Bazaar, the world's largest undercover market. With more than 4,000 stores across 31,000 square metres, you can shop till you drop from everything from tourist tat to textiles and jewels.

Dating from the 15th century, the Grand Bazaar runs across 64 streets and traders are noted for seeking to extract your money for an overpriced item unless you are prepared to haggle. For the experience alone, it can be a cash-free walk-through to sample the hustle and bustle of a city permanently on the move.

Basilica Cistern

While at ground level, Istanbul offers everything and more, its subterranean spaces are just as fascinating. The Basilica Cistern is an ancient chamber that used to work as a water filtration system devised during the Byzantine era.

Fully restored, it allows you to see 330 marble columns, including one of the heads of Medusa and Hen's eye column with a teardrop motif. This piece of engineering is 143m long and 65m wide and can hold 80,000 cubic meters of water.

Taksim Square

6 Gems To Explore In Istanbul - The Wise Traveller - Beyoglu

As much as Istanbul is full of historical delights, travellers will also marvel at city life that continually threads through its many streets. One of the many focal points of this metropolis is Taksim Square, which is packed with hotels, shops, restaurants and notable eateries.

Located on the city's Eastern side in Beyoğlu, the Square is considered the beating heart of modern Istanbul, with the central station of the Istanbul Metro network. Created by Pietro Canonica and inaugurated in 1928, the central monument commemorates the fifth anniversary of the Republic of Turkey's foundation.

Andy Probert - The Wise TravellerAndy Probert is an experienced freelance business travel journalist and PR specialist.