First of all, many other religions have pilgrimages. The Hajj is a massive pilgrimage that Muslims do. There are many other examples. So lots of people who are not Catholic go on pilgrimages relating to their own religion.
If you are talking about non-Catholics going on pilgrimages associated with Catholics, then there are various reasons why they might go. When there is a Catholic pilgrimage, people don't have to prove they are Catholic before they go, so anyone can go. Some may be another denomination of Christianity and so share some beliefs and so might have an interest in going. Some go out of curiousity. Some may go out of a professional capacity, such as a reporter doing some work on the pilgrimage. Some may be brought by some Catholics hoping that they will get some benefit out of it. Some people may be thinking of becoming Catholic and may go on a pilgrimage as part of their exploration in Catholicism. So there are many reasons why a non-Catholic may go on a Catholic pilgrimage.
Catholics are not required to go on pilgrimages to any of the various holy sites throughout the world. Some Catholics never go, others may go on pilgrimages quite frequently.
They typically go to shrines, especially apparition sites of the BVM.
Lourdes
non-catholics.
People still go on pilgrimages, such as Hindus and the Muslims.
People go on pilgrimages to go to a new place where they can freely practice their desired religion without and consequences.
The Vatican is the location of the governing body of the Roman Catholic Church, including the Pope and a rather extensive ecclesiatical bureaucracy. Catholics consider this to be holy and therefore are interested in visiting it.
the main reason they went on pilgrimages is to build their relationship with god
Catholics ARE Christians. Christianity basically splits to: Catholics and non Catholics, the non-Catholics are Protestants, Baptist, Non Demoninational ect. Yet we are all connected because we are all Christians.
Such a marriage would not be valid in the eyes of the Catholic Church. Catholics may marry non-Catholics in the Catholic Church, but they are not permitted to go through a non-Catholic wedding ceremony.
Yes.
No, some people still go on personal pilgrimages. There are some churches who go to places as a group because it represents the major holy place for their religion. Muslims go to Mecca as a pilgrimage.