OTTAWA - Thousands of tourists will flock to Parliament Hill again this summer eager for a peek into the venerable House of Commons, still a dignified chamber despite the buffoonery that often occurs inside.

And once again, thousands will be turned away disappointed, as officials try to shoehorn a crush of visitors into stately structures built for another era.

Meanwhile, plans for a spacious visitors' centre to absorb the restless crowds have been gathering dust as red tape and crumbling stone conspire against the project.

"There's no doubt that there's a crying need,'' says Benoit Morin, an official in charge of Parliament Hill tours.

"We turn away a lot of visitors because of accessibility constraints in the buildings.''

About three million people descend on Parliament Hill each year, a population bigger than the City of Toronto. Many are business visitors meeting MPs or government officials, but at least 1.5 million are tourists.

Last year, just 376,000 people were able to tour the Centre Block, site of the House of Commons, the Senate, the Peace Tower and the freshly renovated Library of Parliament.

A 2003 Ekos Research survey found that 48 per cent of all visitors expecting to tour the building were unable to do so because of the crowds. Morin says that percentage likely hasn't changed much.

And if you don't get the tour, there's not much else to do except admire the exterior of the buildings for perhaps watch the changing-of-the-guard ceremony on the lawn on summer mornings.

"It's either the tour or nothing,'' says Morin, a senior official with the Library of Parliament. "And if you're at the end of the line (at peak times), your chances are nil.''

In recent years, other countries have spent millions on visitor centres to absorb waves of curious citizens drawn to their seats of government, including both the United States and Britain.

But in Canada, a similar proposal has languished on the books since at least 2001 as Public Works copes with the nightmare of renovating the Hill's existing buildings, some of which date back a century or more.

The West Block -- built in 1865, the oldest structure on Parliament Hill -- has been a special sinkhole of trouble. Crumbling mortar and falling stone forced officials to begin renovations years ahead of a planned 2008 start date, at a staggering cost estimated at $770 million.

"That's where we've focused virtually all of our attention to date ... because of how critical it is,'' says Bill Doering, the Public Works official in charge of the so-called parliamentary precinct.

The department is also bracing for complex renovations of the Centre Block. A visitors' centre remains far down the priority list.

"It's unfortunate, it truly is,'' Doering said. "Because of the stage we're at ... it's going to take a little while.''

At the same time, a Commons oversight group known as the Board of Internal Economy is pressing to extend Parliament's jurisdiction beyond the buildings themselves to the surrounding grounds, now under the purview of Public Works.

Any jurisdictional squabble would further complicate decision-making, as Public Works, the National Capital Commission, the RCMP and Parliament need to agree on projects.

Even deciding where to put a visitors' centre is fraught, with some arguing it should be away from Parliament Hill to avoid cluttering the iconic landscape.

The latest feasibility study, however, recommends a 3,500-square-metre structure discreetly constructed on the lawn in front of the Peace Tower.

Costing perhaps $50 million, the so-called welcome centre could offer an alternate educational experience for tourists still unable to get into the Centre Block, says a 2006 report by consultant HOK Canada. Films and displays, for example, could tell the story of Parliament.

Such a facility could also provide security clearance for visitors, who are now funnelled into a small indoor checkpoint immediately behind the Peace Tower.

Some politicians have already complained that the current security arrangement is dangerous, especially in the post 9-11 era.

"A scan serves no purpose once an explosive device has entered the buildings, especially the Centre Block,'' a group of MPs wrote late last year to the Board of Internal Economy.

The HOK Canada report notes the threat posed by bombs can be reduced by screening in a separate visitors' centre on the lawn.

"The dangers from a blast in this proximity to the buildings can be mitigated and controlled through design and construction,'' says the report, obtained under the Access to Information Act.

In the meantime, Morin says tourists arriving in the jam-packed summer months should consider the special evening tours.

"You have significantly greater chances if you decide to come later in the day.''