In this article, you'll find out which airports can fill the time of a longer layover with a guided city visit, sometimes with refreshments and free visas - all for free.

We've put together a list of transfer points and their options for organised trips, along with some tips for when you're travelling on your own.

Istanbul

Istanbul is a beautiful city and definitely worth a separate visit. However, if you're connecting to Istanbul IST and flying Turkish Airlines at the same time, be sure to take advantage of their Tour Istanbul program.

Transportation and refreshments(breakfast, lunch and dinner depending on tour time) are included.

Conditions:

• Change of flights with Turkish Airlines
• Transfer duration - 6 - 24 hours
• Tour duration - 2.5 - 6 hours
• Start of tours - 8:00, 8:30, 9:00, 12:00, 16:00, 18:30
• More information at turkishairlines.com/touristanbul

To participate in the tour, arrive at least 30 minutes before the start time at the Hotel Desk (next to Starbucks).

Beijing

Trip.com's travel agency organizes free tours of Beijing or the Great Wall for all international travelers.

Two tours are scheduled daily as part of the Beijing Express:

• 7:30 a.m.-1 p.m. Great Wall Tour.
• 13:30-21:00 Tour of downtown Beijing

Free tours are only available at Beijing Capital Airport PEK. Tours are not yet available at Beijing's other airport , Daxing PKX.

Terms:

• Connection time - over 8 hours
• Tour duration - 5.5 or 7.5 hours
• Tours start - 7:30 a.m. and 1:30 p.m.
• More information and online tour booking at trip.com/beijingexpress-halfdaylayovertour

The tour does not need to be booked in advance and the meeting point is in the International Arrivals Hall of Terminal 3 of Beijing-Capital PEK Airport near the "Manner Coffee" cafe.

Shanghai

In addition to Beijing, Trip.com also organizes free tours in Shanghai for all international travelers.

There are 3 tours daily on the Shanghai Express:

• 9:00-14:00 Shanghai downtown tour
• 10:00-16:00 Get to know local life by walking around the city centre
• 18:00-23:00 Night cruise on the Huangpu River

Free tours are only available at Shanghai-Pudong PVG Airport. Tours are not yet available at Shanghai's other airport , Hongqiao SHA.

Terms:

• Connection time - over 8 hours
• Tour length - 5 or 6 hours
• Tours start - 9:00, 10:00 and 18:00
• More information and online tour booking at trip.com/hot/shanghaiexpress-halfdaylayovertour

The tour does not need to be booked in advance and the meeting point is in the International Arrivals Hall of Shanghai-Pudong PVG Airport Terminal 1 at the Tourist Information Centre.

Taipei

You will see the capital of Taiwan as part of the tour regardless of the airline you fly with.

There is a morning and afternoon program from Taipei Taoyuan TPE Airport that includes the Shou Sin Fang Cultural Center, Sanxia Temple and Zushi or Chiang Kai-shek Memorial Hall and Longshan Temple.

Conditions:

• Transfer time - 7 - 24 hours
• Tour duration - 4 hours
• Tours start - 8:30 a.m., 2:00 p.m., 6:00 p.m.
• More information and online tour booking at halfdaytour.taiwan.net.tw

Pick up and check in point is at the Tourist Centres in both Terminal 1 and 2 in the arrivals hall - behind passport control. Tour capacity is limited to 18 seats.

Singapore

Singapore is likely to include more than just a few hours in your itinerary when you make your connection.

Even so, it's good to know about Changi' s very well organised tours to get a quick tour of the city. The tours are divided into day and night tours that include light shows at Gardens by the Bay.

Conditions:

• Length of transfer - 5.5 - 24 hours
• Length of tour - 3 hours
• Tours start - 10:00 a.m., 12:00 p.m., 1:00 p.m., 4:00 p.m., 6:00 p.m., 7:00 p.m.
• More information and online booking at changiairport.com/tour

Tour registrations are done at the Free Singapore Tours counters at Terminal 2 and 3 and close one hour before the start time.

Seoul

The advantage of the tour from Incheon ICN in Seoul, South Korea, is the very flexible minimum transfer time.

With just a two-hour transit time, you should be able to make your way to Yonggungsa Temple. There are 7 different programs to choose from ranging from 4 to 6 hours. Transportation is included, or entrance and meals are paid for by each person.

Conditions:

• Transfer time - 2 to 24 hours.
• Tour duration - 4 to 6 hours
• Start of tours - according to the program from 7:00 a.m. to 3:00 p.m.
• More information at airport.kr/tour

Doha

Until 2018, Qatar Airways offered complimentary tours when connecting at Doha DOH.

Currently, full-day tours of Qatar's capital city cost from 115 qar and with Qatar allowing visa-free entry to most countries and very easy transport to/from the airport, it's more worthwhile to explore Doha on your own.

Things to remember when exploring individually

Of course, our list of airports that can be used to explore the nearby city during a layover doesn't end there.

No matter where you are connecting, you can always leave the airport and then return again for your next flight. So what to think about when you're taking a trip individually?

Can I enter the country? Visas are an essential part of any time you want to leave the transit area of an airport. In most cases, you can obtain a visa at the airport upon arrival, but some countries do not have this option. So find out about this single requirement in advance.

How to get to the centre? Forget the cheapest local bus-type options. Transferring is simply a matter of time, and the more you have, the more you'll get out of it. This makes airports with direct rail or metro connections(Amsterdam, Kuala Lumpur, Dubai, Athens and many more) ideal for trips.

We cover transport information from almost every airport in the world in our guides.

Plan to allow time. If it takes 40 minutes to get from the airport, allow an hour - you also have to wait for the connection. Work out in advance how much of the city centre you can cover in the time you have and what sights to avoid.

Again, allow for security checks. By leaving the airport you will not avoid security and possibly passport control again. Therefore, you should still arrive at the airport at least one hour before departure.

In the next installment you can look forward to a list of airlines that will provide you with free accommodation, meals and possibly visa entry during your long layover.