Visitors cannot enter it

Does the green sentence mean "the actual memorial is a part of this building that consists of lit glass beads, which visitors are not allowed to enter it because it is a very narrow space"?

Context:

The French architect Georges-Henri Pingusson’s Mémorial des Martyrs de la Déportation (1962) is one of the earliest architectural memorials to Nazi persecution. It is behind Notre Dame Cathedral in Paris. It is difficult to find, and descent into it is like leaving one world and entering another, as Paris disappears. A bare and simple space encourages contemplation and reflection; the only view out is through a grate overlooking the Seine. The actual memorial to the 200,000 French deportees to the Nazi camps consists of lit glass beads; visitors cannot enter it because its space is narrow and constricted. As in so many memorials, the words of great writers – in this case, French – inscribed on the walls convey what many find too painful to articulate.