Archbishop Rino Fisichella, the special representative for the major ecclesiastical event, said this at a press conference in the Vatican on Thursday.
One of the largest construction sites is the remodelling of the area between Castel Sant'Angelo and St. Peter's Basilica, which is to become an extensive pedestrian zone.
Fisichella praised the cooperation between the church and state authorities, headed by Rome's mayor Roberto Gualtieri.
The left-wing democrat is also the Italian government's special commissioner for the major event and regularly visits the construction sites to see the progress of the work for himself.
Fisichella confirmed that the Pope intends to put the binding announcement document (known as the "Bull") for the Holy Year into effect on 9 May, the Feast of the Ascension.
This will also set out the rules for the remission of ecclesiastical penalties, known as indulgences, for pilgrims.
It is expected that, as in the Holy Year 2000, there will again be special rules for people who are unable to make a personal pilgrimage to Rome for important reasons.
Millions of pilgrims expected
The Vatican will also publish the programme of the year's major events in May.
The programme will include central services and events for specific groups of pilgrims, professional groups, religious associations and the like.
Several hundred thousand pilgrims are expected to attend some of these events.
According to Vatican estimates, more than 30 million tourists are expected to visit Rome throughout the year.
In order to provide spiritual impetus before the opening on Christmas Day this year, a number of cultural events are already planned for the current year, which Fisichella presented on Thursday.
Among other things, individual religious works of art by Marc Chagall (1887-1985) and Salvador Dali (1904-1989) are to be shown in Roman churches.
The surrealist Dali returned to the Catholic faith after 1948 and illustrated Dante's "Divine Comedy" with watercolours, among other works.
A film retrospective is also planned. Among other things, the largely forgotten film "La porta del cielo" (The Door to Heaven) by Vittorio De Sica will be shown.
It was filmed in 1944 despite German occupation on the grounds of the Basilica of St Paul Outside the Walls, which is part of the Vatican grounds.
It tells the story of a pilgrimage.
The only film by writer Curzio Malaparte, "Il Cristo proibito" (The Forbidden Christ) from 1951, will also be shown.
The film deals with the theme of guilt and atonement in the context of the Italian post-war period.
Also an exhibition of icons
An exhibition of icons from Russia and Ukraine and a series of concerts are also planned.
The last of these will be given by the choir of the Sistine Chapel two days before the opening of the Holy Year, on 22 December, in the Roman church of Sant'Ignazio.
The Holy Year is a year-long, worldwide pilgrimage event of the Catholic Church with Rome as its centre.
It regularly takes place every 25 years.
Pope Francis is expected to open the Holy Year 2025 on 24 December 2024.