best by night, especially when approached from the eastern one of Golden Jubilee Footbridges beside Hungerford Bridge. After being closed for many years, the roof terrace and bridge to the Hayward Gallery were reopened in 2011, with the creation of a new external gallery and a roof garden and café, in partnership with the Eden Project in Cornwall. This reopened one of the most interesting pedestrian circulation possibilities of the original design. The roof terrace is reached by the external concrete staircase at the west corner on Queen's Walk near Festival Pier, which also leads to the lower level and the route to Festival Square. A crude disabled ramp, constructed of breeze blocks and bricks, has been added to the walkway between the QEH entrance and the Hayward Gallery. Auditorium The QEH auditorium is a separate building from the foyer. The auditorium building is aligned with the rear of its stage parallel to Waterloo Bridge and the seating area cantilevered out towards the foyer, supported by a massive column containing the emergency escape staircases at the rear. The north-west facade, by Waterloo Bridge, although stained by pollution and rainwater, is a good example of the massive concrete forms popular in 1960s Brutalist architecture in Britain. A slightly raised area, resembling a low stage is provided facing Waterloo Bridge. This may have been intended for outdoor performances. A great concrete "prow", encasing the air conditioning ducting, protrudes towards the Thames along the side of the auditorium at roof level. The walkway area below this feature is on the roof of a utility building, and a branch of the restaurant chain Wahaca has been installed in a set of containers there, in 2012. Ventilation services are provided from a plant room on the roof of the Purcell Room via a massive concrete duct between the buildings leading into the QEH roof, and a concrete tower leading to the concrete duct on the north-east edge of the foyer building roof. The acoustic properties of the Queen Elizabeth Hall are judged to be generally excellent. The acoustical properties of the Hall when examined in 1968 by music critics and engineers following a period of testing, trials and adjustment, were found to be of "general excellence" in the three key areas of: a) Reverberation Time, which in this Hall is mainly adjusted by opening and closing cavities in the vertical wood panels on both sides,