In 1999, archaeologists opened up two tunnels that allow visitors to get a glimpse of pre-existing structures below the visible surface structures. The first, Rosalila, is very short and takes only a few visitors at a time. The famous temple is only barely exposed, and behind thick glass. The other tunnel, Los Jaguares, running along the foundations of Temple 22, was originally 700m in length, but a large section has been closed, reducing it to about 80m.
While fascinating, it’s hard to justify the extra you pay to get in.
