Disadvantages

1- Tourism can often cause environmental damage with things like pollution and forest fires. Even if tourists behave responsibly, the sheer number of them can cause problems. Things like ancient buildings, monuments, and temples often struggle to cope with the vast amounts of tourist traffic and they suffer wear and tear or damage.
2- Often times, most of the tourism industry (travel companies and hotels, for one) in a developing country is actually owned by big foreign companies. They make the major profits, leaving local businesses with relatively little benefit.
3- Tourists can often lack respect for local traditions and culture, not following local dress standards, getting drunk in public or behaving rudely or inappropriately towards locals.
4- Tourism jobs are quite commonly seasonal and insecure with no extra benefits, such as pensions, sick pay, or health care. Some areas can be inundated with visitors during busy times, and then virtually deserted for many months.
5- Although often jobs are created by tourism, most are relatively low level, such as bar work, hotel service, restaurant serving, and so forth. They also have little prospect for promotion.
In conclusion, this is an amazing industry to contribute today's economy. It is a great way for people to spend their money and also for cities to attract other people.

Holly places & shrines and tourism

Religious tourism, also commonly referred to as faith tourism, is a type of tourism, where people travel individually or in groups for pilgrimage, missionary, or leisure (fellowship) purposes. Almost every religion in the world recommends travelling to other places as a tourist due to some goals and recognizes the spirituality of travel. In Quran and other scriptures, various places are given great significance for the roles they play in different belief systems.

Badrinath

Uttarakhand, India, is the sound location of this holy place for Hindus. Nestled within the Himalayas, Badrinath is a sacred place of the god Vishnu. Some believe that the Vyas Caves, just outside this holy town, is where the Sanskrit epic the Mahabharata was written. The area’s main attraction is Badrinath Temple, built in the 9th Century by Garhwal kings. It is primarily a place to worship Vishnu, although other gods are also represented. After visiting the temple, take a spiritual cleanse in one of the area’s natural hot springs, Tapt Kund and Surya Kund. 

Western Wall

the holiest of Jewish sites for Jews located in Jerusalem, Israel, is Western Wall.

After the First Temple had been destroyed by the Babylonians, the Second Temple (built to replace the first) was destroyed by the Romans in 70 AD. Subsequently, the remaining wall, Kotel, or Western Wall, became a place of worship and mourning for the old temples. As a result, it is often called the Wailing Wall. 

Imam Husain’ Shrine 

The Imam Husain Shrine or the Station of Imam Husain ibn Ali in Karbala’ is the burial site of Husain ibn Ali, the third Imam of Islam, in Iraq. It stands on the site of the Mausoleum of Imam Husain, who was a grandson of Muhammad, near the place where he was martyred during the Battle of Karbala’ in 680 C.E. The tomb of Imam Husain is one of the holiest places for Shi‘ites, outside of Mecca and Medina, and many make pilgrimages to the site. Every year, millions of pilgrims visit the city to observe Ashura, which marks the anniversary of Imam Husain’s death. Every year for arba'een rituals that occurs forty days after the Day of Ashura up to 45 million people go to the city of Karbala in Iraq.

An estimated 14 million pilgrims thronged Karbala to mark the annual Arbaeen commemoration in 2016.

Golden Temple

The other place to visit for pilgrims specially for Sikhs is Golden Temple. It was built in the early 1600s from marble and then overlaid with gold leaf. Inside the temple, visitors can find the Guru Granth Sahib, the holy text of Sikhism. Around the temple is a body of water called the Amrit Sarovar, or Pool of Nectar. Within the temple, one impressive site is a dining hall where volunteers serve food to 3,500 people in need.

Palitana

A holy city for Jains is Palitana, Shatrunjaya Hill in Gujarat, India. The holy city of Palitana, is an important place of worship in Jainism, a belief system that revolves around non-violence toward all living things – people, animals, even insects. Shatrunjaya is a hill of steps stretching 591m high. Along the way are 863 marble Jain temples, comprising the holiest place on earth for Jainsm.

Sri Pada

Another famous place in Sri Lanka is Sri Panda for all Buddhists, Christians, Muslims and Hindus. A beautiful holy mountain that everyone can appreciate it and maybe this beauty is the reason why four different religions consider the mountain as a sacred place. A rock formation near the summit takes a different shape in each belief system: Buddhists believe it is the footprint of the Buddha; Muslims believe it is the footprint of the prophet Adam; Hindus believe it is the footprint of Shiva; and, Christians believe it is the footprint of St Thomas.

Imam Reza’s shrine 

Mashhad is the second most populous city in Iran and the capital of Razavi Khorasan Province where Imam Reza’s shrine is located. Imam Reza is the eighth Shi'ite Imam who was poisoned and buried in Mashhad. So, the name Mashhad, meaning the place of martyrdom of Imam Reza and annually millions of pilgrims visit his shrine from all over the world.